Building emission reduction is an important way to achieve China’s carbon peaking and carbon neutrality goals.Aiming at the problem of low carbon economic operation of a photovoltaic energy storage building system,a ...Building emission reduction is an important way to achieve China’s carbon peaking and carbon neutrality goals.Aiming at the problem of low carbon economic operation of a photovoltaic energy storage building system,a multi-time scale optimal scheduling strategy based on model predictive control(MPC)is proposed under the consideration of load optimization.First,load optimization is achieved by controlling the charging time of electric vehicles as well as adjusting the air conditioning operation temperature,and the photovoltaic energy storage building system model is constructed to propose a day-ahead scheduling strategy with the lowest daily operation cost.Second,considering inter-day to intra-day source-load prediction error,an intraday rolling optimal scheduling strategy based on MPC is proposed that dynamically corrects the day-ahead dispatch results to stabilize system power fluctuations and promote photovoltaic consumption.Finally,taking an office building on a summer work day as an example,the effectiveness of the proposed scheduling strategy is verified.The results of the example show that the strategy reduces the total operating cost of the photovoltaic energy storage building system by 17.11%,improves the carbon emission reduction by 7.99%,and the photovoltaic consumption rate reaches 98.57%,improving the system’s low-carbon and economic performance.展开更多
This paper proposes a group synchronization control scheme with prediction in work using haptic media. The scheme adjusts the output timing among multiple terminals and keeps the interactivity high. It outputs positio...This paper proposes a group synchronization control scheme with prediction in work using haptic media. The scheme adjusts the output timing among multiple terminals and keeps the interactivity high. It outputs position information by predicting the future position later than the position included in the last-received information by a fixed amount of time. It also advances the output time of position information at each local terminal by the same amount of time. We deal with two different types of work using haptic media so as to demonstrate the effectiveness of the scheme. We assess the output quality of haptic media for the two types of work subjectively and objectively by Quality of Experience (QoE) assessment. We further clarify the relationship between subjective and objective assessment results.展开更多
The universal creep equation relates creep behavior (ε/ε 0) to aging time (t a), coefficient of retardation time (β), and intrinsic time (t 0). The relation was used to treat the creep experimental ...The universal creep equation relates creep behavior (ε/ε 0) to aging time (t a), coefficient of retardation time (β), and intrinsic time (t 0). The relation was used to treat the creep experimental data for pipe specimens of polypropylene block copolymer (PPC), which were aged for different days (short term) and tested under different stress levels at a certain temperature. Then unified master lines were constructed with the treated data and curves according to the universal equation. The master straight lines can be used for extrapolation to predict the long term creep behavior and lifetime of the pipe materials of PPC in the same way as plate materials.展开更多
This paper proposed a back propagation neural network model for predictive block-matching. Predictive block-matching is a way to significantly decrease the computational complexity of motion estimation, but the tradit...This paper proposed a back propagation neural network model for predictive block-matching. Predictive block-matching is a way to significantly decrease the computational complexity of motion estimation, but the traditional prediction model was proposed 26 years ago. It is straight forward but not accurate enough. The proposed back propagation neural network has 5 inputs, 5 neutrons and 1 output. Because of its simplicity, it requires very little calculation power which is negligible compared with existing computation complexity. The test results show 10% - 30% higher prediction accuracy and PSNR improvement up to 0.3 dB. The above advantages make it a feasible replacement of the current model.展开更多
Daily output from the hindcasts by the NCEP Climate Forecast System version 2 （CFSv2） is analyzed to understand CFSv2＇s skill in forecasting wintertime atmospheric blocking in the Northern Hemisphere. Prediction sk...Daily output from the hindcasts by the NCEP Climate Forecast System version 2 （CFSv2） is analyzed to understand CFSv2＇s skill in forecasting wintertime atmospheric blocking in the Northern Hemisphere. Prediction skills of sector blocking, sector-blocking episodes, and blocking onset/decay are assessed with a focus on the Euro-Atlantic sector （20°W-45°E） and the Pacific sector （160°E 135°W）. Features of associated circulation and climate patterns are also examined. The CFSv2 well captures the observed features of longitudinal distribution of blocking activity, but underestimates blocking frequency and intensity and shows a decreasing trend in blocking frequency with increasing forecast lead time. Within 14-day lead time, the Euro-Atlantic sector blocking receives a higher skill than the Pacific sector blocking. Skillful forecast （taking the hit rate of 50~ as a criterion） can be obtained up to 9 days in the Euro-Atlantic sector, which is slightly longer than that in the Pacific sector （7 days）. The forecast skill of sector-blocking episodes is slightly lower than that of sector blocking in both sectors, and it is slightly higher in the Euro-Atlantic sector than in the Pacific sector. Compared to block onset, the skill for block decay is lower in the Euro-Atlantic sector, slightly higher in the Pacific sector during the early three days but lower after three days in lead time. In both the Euro-Atlantic and the Pacific sectors, a local dipole pattern in 500-hPa geopotential height associated with blocking is well presented in the CFSv2 prediction, but the wave-train like pattern that is far away from the blocking sector can only maintain in the forecast of relative short lead time. The CFSv2 well reproduces the observed characteristics of local temperature and precipitation anomalies associated with blocking.展开更多
With the reversible data hiding method based on pixel-value-ordering,data are embedded through the modification of the maximum and minimum values of a block.A significant relationship exists between the embedding perf...With the reversible data hiding method based on pixel-value-ordering,data are embedded through the modification of the maximum and minimum values of a block.A significant relationship exists between the embedding performance and the block size.Traditional pixel-value-ordering methods utilize pixel blocks with a fixed size to embed data;the smaller the pixel blocks,greater is the embedding capacity.However,it tends to result in the deterioration of the quality of the marked image.Herein,a novel reversible data hiding method is proposed by incorporating a block merging strategy into Li et al.’s pixel-value-ordering method,which realizes the dynamic control of block size by considering the image texture.First,the cover image is divided into non-overlapping 2×2 pixel blocks.Subsequently,according to their complexity,similarity and thresholds,these blocks are employed for data embedding through the pixel-value-ordering method directly or after being emerged into 2×4,4×2,or 4×4 sized blocks.Hence,smaller blocks can be used in the smooth region to create a high embedding capacity and larger blocks in the texture region to maintain a high peak signal-to-noise ratio.Experimental results prove that the proposed method is superior to the other three advanced methods.It achieves a high embedding capacity while maintaining low distortion and improves the embedding performance of the pixel-value-ordering algorithm.展开更多
Hiding secret data in digital images is one of the major researchfields in information security.Recently,reversible data hiding in encrypted images has attracted extensive attention due to the emergence of cloud servi...Hiding secret data in digital images is one of the major researchfields in information security.Recently,reversible data hiding in encrypted images has attracted extensive attention due to the emergence of cloud services.This paper proposes a novel reversible data hiding method in encrypted images based on an optimal multi-threshold block labeling technique(OMTBL-RDHEI).In our scheme,the content owner encrypts the cover image with block permutation,pixel permutation,and stream cipher,which preserve the in-block correlation of pixel values.After uploading to the cloud service,the data hider applies the prediction error rearrangement(PER),the optimal threshold selection(OTS),and the multi-threshold labeling(MTL)methods to obtain a compressed version of the encrypted image and embed secret data into the vacated room.The receiver can extract the secret,restore the cover image,or do both according to his/her granted authority.The proposed MTL labels blocks of the encrypted image with a list of threshold values which is optimized with OTS based on the features of the current image.Experimental results show that labeling image blocks with the optimized threshold list can efficiently enlarge the amount of vacated room and thus improve the embedding capacity of an encrypted cover image.Security level of the proposed scheme is analyzed and the embedding capacity is compared with state-of-the-art schemes.Both are concluded with satisfactory performance.展开更多
In order to accurately predict the production performance of coalbed methane(CBM)wells and to formulate a reasonable production system,this paper established a coal reservoir permeability model considering the influen...In order to accurately predict the production performance of coalbed methane(CBM)wells and to formulate a reasonable production system,this paper established a coal reservoir permeability model considering the influence of pulverized coal blockage.Then,on the basis of this model,the flow velocity sensitivity(FVS)experimental data of 15 groups of coal samples taken from the Baode Block,Qinshui Basin,Liulin Block,Hancheng Block,and the Huanglong Coalfield were fitted to determine the permeability models for different coal samples.On this basis,this newly established permeability model was incorporated into a previously developed CBM well performance analysis software,and production history matching was carried out on two CBM wells.Finally,the effects of the parameters of pulverized coal blockage on the permeability of coal reservoirs and the production performance of CBM wells were studied by taking the fitting parameters of CBM Well W1 as the reference.And the following research results are obtained.First,this new model considering the influence of pulverized coal blockage can quantitatively describe the variation of coal reservoir permeability with fluid velocity.In addition,this model can be incorporated into a CBM numerical simulation software or a CBM well performance analysis software to apply it in a wide range.Second,the coal reservoir permeability is less affected by pulverized coal blockage in the Baode Block,but this effect shall not be ignored in the Qinshui Basin and the Huanglong Coalfield.Third,the greater the theoretical maximum permeability damage degree(D_(max))and the permeability damage degree index(n)are,the lower the relative flow velocity(v0.5)corresponding to the critical flow velocity of pulverized coal blockage is and the more obvious the effect of pulverized coal blockage on coal reservoir permeability is.Fourth,in order to reduce the adverse effect of pulverized coal blockage on coal reservoir permeability,it is suggested to reduce the production pressure difference appropriately in the process of production,especially in the initial stage of gas production,so as to avoid severe damage to coal reservoir permeability.展开更多
In recent years,great progress has been made in geologic evaluation,engineering test and development optimization of the Lower Cambrian Wufeng FmeLower Silurian Longmaxi Fm shale gas in the Sichuan Basin,and the main ...In recent years,great progress has been made in geologic evaluation,engineering test and development optimization of the Lower Cambrian Wufeng FmeLower Silurian Longmaxi Fm shale gas in the Sichuan Basin,and the main shale gas exploitation technologies have been un-derstood preliminarily.In addition,scale productivity construction has been completed in Jiaoshiba,Changning and Weiyuan blocks.In this paper,the Wufeng FmeLongmaxi Fm shale gas wells in Changning Block were taken as the study object to provide technical reference for the development design of similar shale-gas horizontal wells.The technology combining geology with engineering,dynamic with static,and statistical analysis with simulation prediction was applied to quantify the main factors controlling shale-gas well productivity,develop the shale-gas well production prediction model,and optimize the key technical parameters of geologic target of shale-gas horizontal wells in the block(e.g.roadway orientation,location and spacing,horizontal section length and gas well production index).In order to realize high productivity of shale gas wells,it is necessary to maximize the included angle between the horizontal section orientation and the maximum major stress and fracture development direction,deploy horizontal-well roadway in top-quality shale layers,and drill the horizontal section in type I reservoirs over 1000 m long.It is concluded that high productivity of shale gas wells is guaranteed by the horizontal-well wellbore integrity and the optimized low-viscosity slickwater and ceramsite fracturing technology for complex fracture creation.Based on the research results,the technical policies for shale gas development of Changning Block are prepared and a guidance and reference are provided for the shale gas development and productivity construction in the block and the development design of similar shale-gas horizontal wells.展开更多
文摘Building emission reduction is an important way to achieve China’s carbon peaking and carbon neutrality goals.Aiming at the problem of low carbon economic operation of a photovoltaic energy storage building system,a multi-time scale optimal scheduling strategy based on model predictive control(MPC)is proposed under the consideration of load optimization.First,load optimization is achieved by controlling the charging time of electric vehicles as well as adjusting the air conditioning operation temperature,and the photovoltaic energy storage building system model is constructed to propose a day-ahead scheduling strategy with the lowest daily operation cost.Second,considering inter-day to intra-day source-load prediction error,an intraday rolling optimal scheduling strategy based on MPC is proposed that dynamically corrects the day-ahead dispatch results to stabilize system power fluctuations and promote photovoltaic consumption.Finally,taking an office building on a summer work day as an example,the effectiveness of the proposed scheduling strategy is verified.The results of the example show that the strategy reduces the total operating cost of the photovoltaic energy storage building system by 17.11%,improves the carbon emission reduction by 7.99%,and the photovoltaic consumption rate reaches 98.57%,improving the system’s low-carbon and economic performance.
文摘This paper proposes a group synchronization control scheme with prediction in work using haptic media. The scheme adjusts the output timing among multiple terminals and keeps the interactivity high. It outputs position information by predicting the future position later than the position included in the last-received information by a fixed amount of time. It also advances the output time of position information at each local terminal by the same amount of time. We deal with two different types of work using haptic media so as to demonstrate the effectiveness of the scheme. We assess the output quality of haptic media for the two types of work subjectively and objectively by Quality of Experience (QoE) assessment. We further clarify the relationship between subjective and objective assessment results.
文摘The universal creep equation relates creep behavior (ε/ε 0) to aging time (t a), coefficient of retardation time (β), and intrinsic time (t 0). The relation was used to treat the creep experimental data for pipe specimens of polypropylene block copolymer (PPC), which were aged for different days (short term) and tested under different stress levels at a certain temperature. Then unified master lines were constructed with the treated data and curves according to the universal equation. The master straight lines can be used for extrapolation to predict the long term creep behavior and lifetime of the pipe materials of PPC in the same way as plate materials.
文摘This paper proposed a back propagation neural network model for predictive block-matching. Predictive block-matching is a way to significantly decrease the computational complexity of motion estimation, but the traditional prediction model was proposed 26 years ago. It is straight forward but not accurate enough. The proposed back propagation neural network has 5 inputs, 5 neutrons and 1 output. Because of its simplicity, it requires very little calculation power which is negligible compared with existing computation complexity. The test results show 10% - 30% higher prediction accuracy and PSNR improvement up to 0.3 dB. The above advantages make it a feasible replacement of the current model.
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2010CB428606 and 2014CB950900)China Meteorological Administration Special Public Welfare Research Fund(GYHY201206017)+1 种基金National Science and Technology Support Program of China(2009BAC51B05)LASW State Key Laboratory Special Fund(2013LASW-A05)
文摘Daily output from the hindcasts by the NCEP Climate Forecast System version 2 （CFSv2） is analyzed to understand CFSv2＇s skill in forecasting wintertime atmospheric blocking in the Northern Hemisphere. Prediction skills of sector blocking, sector-blocking episodes, and blocking onset/decay are assessed with a focus on the Euro-Atlantic sector （20°W-45°E） and the Pacific sector （160°E 135°W）. Features of associated circulation and climate patterns are also examined. The CFSv2 well captures the observed features of longitudinal distribution of blocking activity, but underestimates blocking frequency and intensity and shows a decreasing trend in blocking frequency with increasing forecast lead time. Within 14-day lead time, the Euro-Atlantic sector blocking receives a higher skill than the Pacific sector blocking. Skillful forecast （taking the hit rate of 50~ as a criterion） can be obtained up to 9 days in the Euro-Atlantic sector, which is slightly longer than that in the Pacific sector （7 days）. The forecast skill of sector-blocking episodes is slightly lower than that of sector blocking in both sectors, and it is slightly higher in the Euro-Atlantic sector than in the Pacific sector. Compared to block onset, the skill for block decay is lower in the Euro-Atlantic sector, slightly higher in the Pacific sector during the early three days but lower after three days in lead time. In both the Euro-Atlantic and the Pacific sectors, a local dipole pattern in 500-hPa geopotential height associated with blocking is well presented in the CFSv2 prediction, but the wave-train like pattern that is far away from the blocking sector can only maintain in the forecast of relative short lead time. The CFSv2 well reproduces the observed characteristics of local temperature and precipitation anomalies associated with blocking.
文摘With the reversible data hiding method based on pixel-value-ordering,data are embedded through the modification of the maximum and minimum values of a block.A significant relationship exists between the embedding performance and the block size.Traditional pixel-value-ordering methods utilize pixel blocks with a fixed size to embed data;the smaller the pixel blocks,greater is the embedding capacity.However,it tends to result in the deterioration of the quality of the marked image.Herein,a novel reversible data hiding method is proposed by incorporating a block merging strategy into Li et al.’s pixel-value-ordering method,which realizes the dynamic control of block size by considering the image texture.First,the cover image is divided into non-overlapping 2×2 pixel blocks.Subsequently,according to their complexity,similarity and thresholds,these blocks are employed for data embedding through the pixel-value-ordering method directly or after being emerged into 2×4,4×2,or 4×4 sized blocks.Hence,smaller blocks can be used in the smooth region to create a high embedding capacity and larger blocks in the texture region to maintain a high peak signal-to-noise ratio.Experimental results prove that the proposed method is superior to the other three advanced methods.It achieves a high embedding capacity while maintaining low distortion and improves the embedding performance of the pixel-value-ordering algorithm.
基金the Ministry of Science and Technology of Taiwan,Grant Number MOST 110-2221-E-507-003.
文摘Hiding secret data in digital images is one of the major researchfields in information security.Recently,reversible data hiding in encrypted images has attracted extensive attention due to the emergence of cloud services.This paper proposes a novel reversible data hiding method in encrypted images based on an optimal multi-threshold block labeling technique(OMTBL-RDHEI).In our scheme,the content owner encrypts the cover image with block permutation,pixel permutation,and stream cipher,which preserve the in-block correlation of pixel values.After uploading to the cloud service,the data hider applies the prediction error rearrangement(PER),the optimal threshold selection(OTS),and the multi-threshold labeling(MTL)methods to obtain a compressed version of the encrypted image and embed secret data into the vacated room.The receiver can extract the secret,restore the cover image,or do both according to his/her granted authority.The proposed MTL labels blocks of the encrypted image with a list of threshold values which is optimized with OTS based on the features of the current image.Experimental results show that labeling image blocks with the optimized threshold list can efficiently enlarge the amount of vacated room and thus improve the embedding capacity of an encrypted cover image.Security level of the proposed scheme is analyzed and the embedding capacity is compared with state-of-the-art schemes.Both are concluded with satisfactory performance.
基金supported by the National Major Science and Technology Project“Development of CBM quantitative production technology and equipment”(No.:2016ZX05042-004).
文摘In order to accurately predict the production performance of coalbed methane(CBM)wells and to formulate a reasonable production system,this paper established a coal reservoir permeability model considering the influence of pulverized coal blockage.Then,on the basis of this model,the flow velocity sensitivity(FVS)experimental data of 15 groups of coal samples taken from the Baode Block,Qinshui Basin,Liulin Block,Hancheng Block,and the Huanglong Coalfield were fitted to determine the permeability models for different coal samples.On this basis,this newly established permeability model was incorporated into a previously developed CBM well performance analysis software,and production history matching was carried out on two CBM wells.Finally,the effects of the parameters of pulverized coal blockage on the permeability of coal reservoirs and the production performance of CBM wells were studied by taking the fitting parameters of CBM Well W1 as the reference.And the following research results are obtained.First,this new model considering the influence of pulverized coal blockage can quantitatively describe the variation of coal reservoir permeability with fluid velocity.In addition,this model can be incorporated into a CBM numerical simulation software or a CBM well performance analysis software to apply it in a wide range.Second,the coal reservoir permeability is less affected by pulverized coal blockage in the Baode Block,but this effect shall not be ignored in the Qinshui Basin and the Huanglong Coalfield.Third,the greater the theoretical maximum permeability damage degree(D_(max))and the permeability damage degree index(n)are,the lower the relative flow velocity(v0.5)corresponding to the critical flow velocity of pulverized coal blockage is and the more obvious the effect of pulverized coal blockage on coal reservoir permeability is.Fourth,in order to reduce the adverse effect of pulverized coal blockage on coal reservoir permeability,it is suggested to reduce the production pressure difference appropriately in the process of production,especially in the initial stage of gas production,so as to avoid severe damage to coal reservoir permeability.
文摘In recent years,great progress has been made in geologic evaluation,engineering test and development optimization of the Lower Cambrian Wufeng FmeLower Silurian Longmaxi Fm shale gas in the Sichuan Basin,and the main shale gas exploitation technologies have been un-derstood preliminarily.In addition,scale productivity construction has been completed in Jiaoshiba,Changning and Weiyuan blocks.In this paper,the Wufeng FmeLongmaxi Fm shale gas wells in Changning Block were taken as the study object to provide technical reference for the development design of similar shale-gas horizontal wells.The technology combining geology with engineering,dynamic with static,and statistical analysis with simulation prediction was applied to quantify the main factors controlling shale-gas well productivity,develop the shale-gas well production prediction model,and optimize the key technical parameters of geologic target of shale-gas horizontal wells in the block(e.g.roadway orientation,location and spacing,horizontal section length and gas well production index).In order to realize high productivity of shale gas wells,it is necessary to maximize the included angle between the horizontal section orientation and the maximum major stress and fracture development direction,deploy horizontal-well roadway in top-quality shale layers,and drill the horizontal section in type I reservoirs over 1000 m long.It is concluded that high productivity of shale gas wells is guaranteed by the horizontal-well wellbore integrity and the optimized low-viscosity slickwater and ceramsite fracturing technology for complex fracture creation.Based on the research results,the technical policies for shale gas development of Changning Block are prepared and a guidance and reference are provided for the shale gas development and productivity construction in the block and the development design of similar shale-gas horizontal wells.
