为提升虚拟电厂(virtual power plant,VPP)参与电力市场的经济性与调控协调性,提出一种基于分层分区调控的虚拟电厂市场多时间尺度竞价策略。首先,定义虚拟机组作为调度与交易统一建模单元,依据电网拓扑结构与过载风险构建分区聚合策略...为提升虚拟电厂(virtual power plant,VPP)参与电力市场的经济性与调控协调性,提出一种基于分层分区调控的虚拟电厂市场多时间尺度竞价策略。首先,定义虚拟机组作为调度与交易统一建模单元,依据电网拓扑结构与过载风险构建分区聚合策略,进一步构建其外特性表征模型以反映虚拟电厂可调节能力。其次,建立涵盖日前与实时市场的多时间尺度竞价模型,并利用库恩-塔克(Karush-Kuhn-Tucker, KKT)条件将其转化为单层优化问题以降低求解复杂度。最后,通过算例验证所提模型的有效性。结果表明,该策略可在保障网络安全与隐私保护的基础上,有效降低建模维度;可实现VPP在多时间尺度市场中的协调竞价,与采用固定报价和仅考虑日前市场相比,VPP收益分别提升了15.8%和17.2%,增强了VPP的市场适应能力与收益水平。展开更多
Ignition timing control is of great importance in homogeneous charge compression ignition engines. The effect of hydrogen addition on methane combustion was investigated using a CHEMKIN multi-zone model. Results show ...Ignition timing control is of great importance in homogeneous charge compression ignition engines. The effect of hydrogen addition on methane combustion was investigated using a CHEMKIN multi-zone model. Results show that hydrogen addition advances ignition tim- ing and enhances peak pressure and temperature. A brief analysis of chemical kinetics of methane blending hydrogen is also performed in order to investigate the scope of its appli- cation, and the analysis suggests that OH radical plays an important role in the oxidation. Hydrogen addition increases NOx while decreasing HC and CO emissions. Exhaust gas recir- culation （EGR） also advances ignition timing; however, its effects on emissions are generally the opposite. By adjusting the hydrogen addition and EGR rate, the ignition timing can be regulated with a low emission level. Investigation into zones suggests that NOx is mostly formed in core zones while HC and CO mostly originate in the crevice and the quench layer.展开更多
The optimization of multi-zone residential heating,ventilation,and air conditioning(HVAC)control is not an easy task due to its complex dynamic thermal model and the uncertainty of occupant-driven cooling loads.Deep r...The optimization of multi-zone residential heating,ventilation,and air conditioning(HVAC)control is not an easy task due to its complex dynamic thermal model and the uncertainty of occupant-driven cooling loads.Deep reinforcement learning(DRL)methods have recently been proposed to address the HVAC control problem.However,the application of single-agent DRL formulti-zone residential HVAC controlmay lead to non-convergence or slow convergence.In this paper,we propose MAQMC(Multi-Agent deep Q-network for multi-zone residential HVAC Control)to address this challenge with the goal of minimizing energy consumption while maintaining occupants’thermal comfort.MAQMC is divided into MAQMC2(MAQMC with two agents:one agent controls the temperature of each zone,and the other agent controls the humidity of each zone)and MAQMC3(MAQMC with three agents:three agents control the temperature and humidity of three zones,respectively).The experimental results showthatMAQMC3 can reduce energy consumption by 6.27%andMAQMC2 by 3.73%compared with the fixed point;compared with the rule-based,MAQMC3 andMAQMC2 respectively can reduce 61.89%and 59.07%comfort violation.In addition,experiments with different regional weather data demonstrate that the well-trained MAQMC RL agents have the robustness and adaptability to unknown environments.展开更多
As buildings evolve to meet the challenges of energy efficiency and indoor comfort,phase change materials(PCM)emerge as a promising solution due to their ability to store and release latent heat.This paper explores th...As buildings evolve to meet the challenges of energy efficiency and indoor comfort,phase change materials(PCM)emerge as a promising solution due to their ability to store and release latent heat.This paper explores the transformative impact of incorporating PCMon the hygrothermal dynamics of multi-zone constructions.The study focuses on analyzing heat transfer,particularly through thermal conduction,in a wall containing PCM.A novel approach was proposed,wherein the studied system(sensitive balance)interacts directly with a latent balance to realistically define the behavior of specific humidity and mass flow rates.In addition,a numerical model implemented in MATLAB software has been developed to investigate the effect of integrating PCM on the hygrothermal balances inside the building.The obtained results indicate a consistent response in internal temperatures,specific humidity,and mass flow rates,with temperature differences ranging from 5℃to 13℃and a maximum phase shift of 13 h.In addition,the findings provided valuable insights into optimizing the design and performance of multi-zone constructions,offering a sustainable pathway for enhancing building resilience and occupant well-being.展开更多
In this paper,a series of specific studies were carried out to investigate the complex form of fracture networks and figure out the multi-scale flowing laws of nano/micro poresecomplex fracture networks-wellbore durin...In this paper,a series of specific studies were carried out to investigate the complex form of fracture networks and figure out the multi-scale flowing laws of nano/micro poresecomplex fracture networks-wellbore during the development of shale reservoirs by means of horizontal well fracturing.First,hydraulic fractures were induced by means of Brazilian splitting tests.Second,the forms of the hydraulic fractures inside the rock samples were observed by means of X-ray CT scanning to measure the opening of hydraulic fractures.Third,based on the multi-scale unified flowing model,morphological description of fractures and gas flowing mechanism in the matrixecomplex fracture networkewellbore,the productivity equation of single-stage horizontal well fracturing which includes diffusion,slipping and desorption was established.And fourthly,a productivity prediction model of horizontal well multi-stage fracturing in the shale reservoir was established considering the interference between the multi-stage fracturing zones and the pressure drop in the horizontal wellbore.The following results were obtained.First,hydraulic fractures are in the form of a complex network.Second,the measured opening of hydraulic fractures is in the range of 4.25-453 mm,averaging 112 mm.Third,shale gas flowing in different shapes of fracture networks follows different nonlinear flowing laws.Forth,as the fracture density in the strongly stimulated zones rises and the distribution range of the hydraulic fractures in strongly/weakly stimulated zones enlarges,gas production increases gradually.As the interference occurs in the flowing zones of fracture networks between fractured sections,the increasing amplitude of gas production rates decreases.Fifth,when the length of a simulated horizontal well is 1500 m and the half length of a fracture network in the strongly stimulated zone is 100 m,the productivity effect of stage 10 fracturing is the best.Therefore,it is necessary to control fracturing degree reasonably and optimize fracturing parameters,so as to provide a theoretical support for the optimization design of shale gas reservoir fracturing.展开更多
To enhance the comprehension of flow characteristics and enrich the well-test theory of slanted wells,this study established a well-test model for a slanted well in a heterogeneous multi-zonal reservoir.The model cons...To enhance the comprehension of flow characteristics and enrich the well-test theory of slanted wells,this study established a well-test model for a slanted well in a heterogeneous multi-zonal reservoir.The model considered closed boundaries at both the top and bottom,as well as an external boundary with infinite,closed,or constant pressure on the horizontal plane.We took the bi-zonal composite model as an example to carry out concrete analysis.Various contemporary mathematical techniques,including Laplace integral transformation,separation of variables,and eigenfunction methods,were employed to solve the model.The pressure solution in real space was obtained through Duhamel's principle and Stehfest numerical inversion,then analytical curves created,and flow stages were defined for a slanted well in a bi-zonal composite reservoir.In addition,we performed a sensitivity analysis on some parameters affecting the curves.For a tri-zonal composite model,we also plotted the well-test curves and categorized them.Finally,we validated the model through the interpretation of an example well.The results show that the fluid flow of a slanted well in a bi-zonal composite reservoir can be divided into seven main stages,including wellbore storage effect(WSE)stage,skin effect(SE)stage,linear flow(LF)stage,radial flow(RF)stage of the 1st zone,transitional flow(TF)stage from the 1st to the 2nd zone,RF stage of the 2nd zone,and the external boundary response stage.The position of the pressure curve at the SE stage and LF stage decreases as the length and inclination angle increase.Correspondingly,the pressure curve at the RF stage of the 2nd zone and external boundary response stage decreases with increasing mobility ratio.Furthermore,as the radius of the 1st zone increases,the pressure curve at the RF stage of the 1st zone and the TF stage shifts towards the right.The established model and plotted curves provide a theoretical basis for further studies on the flow behavior of slanted wells in composite reservoirs.展开更多
目的探讨生境成像(habitat imaging,HI)无创定量可视化前列腺癌(prostate cancer,PCa)分区异质性并预测其危险度的可行性。材料与方法回顾性收集2018年1月至2024年8月在西京医院行多参数磁共振成像(multi-parameteric magnetic resonanc...目的探讨生境成像(habitat imaging,HI)无创定量可视化前列腺癌(prostate cancer,PCa)分区异质性并预测其危险度的可行性。材料与方法回顾性收集2018年1月至2024年8月在西京医院行多参数磁共振成像(multi-parameteric magnetic resonance imaging,mpMRI)扫描,包括扩散加权成像、体素内非相干运动加权成像和扩散峰度成像,并经根治性前列腺切除术(radical prostatectomy,RP)后病理证实为PCa的147例患者的临床及影像资料,以7∶3分为训练集和测试集。根据RP结果分为移行区(transition zone,TZ)和外周区(peripheral zone,PZ)PCa。整合每体素表观扩散系数(apparent diffusion coefficient,ADC)、灌注分数(perfusion fraction,f)和平均峰度(mean kurtosis,MK)值,划分生境亚区,生成生境地图,从临床、病理、影像多维度比较PZ和TZ PCa间差异。根据2019版国际泌尿病理协会(International Society of Urological Pathology,ISUP)指南,匹配生境地图与RP标本以评估各亚区ISUP分级,将患者分为低危组(ISUP≤2)和高危组(ISUP≥3)。logistic回归分析高危PCa相关特征并构建基于分区的HI(zone-based HI,zHI)-临床影像模型评估危险度,并评估模型效能。结果根据肘部法所示最佳聚类簇数划分3个生境亚区,生境1较生境2、3的ADC、f值更低,MK值更高。相较于TZ,PZ PCa患者临床、病理特征更恶,生境1占比更高。logistic回归分析示解剖分区(OR=3.50,95%CI:1.01~12.09)和生境1占比(OR=3.63,95%CI:1.37~9.62)是高危PCa的独立危险因素(P<0.05)。zHI-临床影像模型评估危险度在训练集和测试集的曲线下面积(area under the curve,AUC)分别为0.889(95%CI:0.822~0.955)和0.883(95%CI:0.740~0.925)。结论本研究多维度验证了PCa分区异质性,并基于解剖分区和HI特征构建模型,对PCa危险度的无创定量可视化预测具有增益效能。展开更多
采用由两方程k-ω模式推导得到的k-g模式数值模拟完整飞机构形的跨声速大迎角流场。由于k-g模式具有勿需使用到物面的法向距离、简单的源项和直接的边界条件等特点,可以方便地推广到包含复杂外形的多块网格系统。与雷诺平均N av ier-S t...采用由两方程k-ω模式推导得到的k-g模式数值模拟完整飞机构形的跨声速大迎角流场。由于k-g模式具有勿需使用到物面的法向距离、简单的源项和直接的边界条件等特点,可以方便地推广到包含复杂外形的多块网格系统。与雷诺平均N av ier-S tokes方程组的求解方法类似,k-g模式方程也采用显式R unge-K u tta方法进行时间推进,用中心加人工粘性格式进行空间离散。采用相同的方法数值模拟NA SA TN D-712翼身组合体标模迎角为12.5°和26.2°的流场来检验程序的可靠性,与可获得的实验数据进行对比分析并获得满意结果。与此同时,还使用了B a ldw in-Lom ax代数模式以作比较。展开更多
文摘为提升虚拟电厂(virtual power plant,VPP)参与电力市场的经济性与调控协调性,提出一种基于分层分区调控的虚拟电厂市场多时间尺度竞价策略。首先,定义虚拟机组作为调度与交易统一建模单元,依据电网拓扑结构与过载风险构建分区聚合策略,进一步构建其外特性表征模型以反映虚拟电厂可调节能力。其次,建立涵盖日前与实时市场的多时间尺度竞价模型,并利用库恩-塔克(Karush-Kuhn-Tucker, KKT)条件将其转化为单层优化问题以降低求解复杂度。最后,通过算例验证所提模型的有效性。结果表明,该策略可在保障网络安全与隐私保护的基础上,有效降低建模维度;可实现VPP在多时间尺度市场中的协调竞价,与采用固定报价和仅考虑日前市场相比,VPP收益分别提升了15.8%和17.2%,增强了VPP的市场适应能力与收益水平。
基金This work was supported by the Natural Science Foundation of Anhui Province （No.090412030）.
文摘Ignition timing control is of great importance in homogeneous charge compression ignition engines. The effect of hydrogen addition on methane combustion was investigated using a CHEMKIN multi-zone model. Results show that hydrogen addition advances ignition tim- ing and enhances peak pressure and temperature. A brief analysis of chemical kinetics of methane blending hydrogen is also performed in order to investigate the scope of its appli- cation, and the analysis suggests that OH radical plays an important role in the oxidation. Hydrogen addition increases NOx while decreasing HC and CO emissions. Exhaust gas recir- culation （EGR） also advances ignition timing; however, its effects on emissions are generally the opposite. By adjusting the hydrogen addition and EGR rate, the ignition timing can be regulated with a low emission level. Investigation into zones suggests that NOx is mostly formed in core zones while HC and CO mostly originate in the crevice and the quench layer.
基金supported by Primary Research and Development Plan of China(No.2020YFC2006602)National Natural Science Foundation of China(Nos.62072324,61876217,61876121,61772357)+2 种基金University Natural Science Foundation of Jiangsu Province(No.21KJA520005)Primary Research and Development Plan of Jiangsu Province(No.BE2020026)Natural Science Foundation of Jiangsu Province(No.BK20190942).
文摘The optimization of multi-zone residential heating,ventilation,and air conditioning(HVAC)control is not an easy task due to its complex dynamic thermal model and the uncertainty of occupant-driven cooling loads.Deep reinforcement learning(DRL)methods have recently been proposed to address the HVAC control problem.However,the application of single-agent DRL formulti-zone residential HVAC controlmay lead to non-convergence or slow convergence.In this paper,we propose MAQMC(Multi-Agent deep Q-network for multi-zone residential HVAC Control)to address this challenge with the goal of minimizing energy consumption while maintaining occupants’thermal comfort.MAQMC is divided into MAQMC2(MAQMC with two agents:one agent controls the temperature of each zone,and the other agent controls the humidity of each zone)and MAQMC3(MAQMC with three agents:three agents control the temperature and humidity of three zones,respectively).The experimental results showthatMAQMC3 can reduce energy consumption by 6.27%andMAQMC2 by 3.73%compared with the fixed point;compared with the rule-based,MAQMC3 andMAQMC2 respectively can reduce 61.89%and 59.07%comfort violation.In addition,experiments with different regional weather data demonstrate that the well-trained MAQMC RL agents have the robustness and adaptability to unknown environments.
基金supported in entire part by the Biomaterials and Transport Phenomena LaboratoryAgreementNo.30303-12-2003,at theUniversity of Medea.
文摘As buildings evolve to meet the challenges of energy efficiency and indoor comfort,phase change materials(PCM)emerge as a promising solution due to their ability to store and release latent heat.This paper explores the transformative impact of incorporating PCMon the hygrothermal dynamics of multi-zone constructions.The study focuses on analyzing heat transfer,particularly through thermal conduction,in a wall containing PCM.A novel approach was proposed,wherein the studied system(sensitive balance)interacts directly with a latent balance to realistically define the behavior of specific humidity and mass flow rates.In addition,a numerical model implemented in MATLAB software has been developed to investigate the effect of integrating PCM on the hygrothermal balances inside the building.The obtained results indicate a consistent response in internal temperatures,specific humidity,and mass flow rates,with temperature differences ranging from 5℃to 13℃and a maximum phase shift of 13 h.In addition,the findings provided valuable insights into optimizing the design and performance of multi-zone constructions,offering a sustainable pathway for enhancing building resilience and occupant well-being.
文摘In this paper,a series of specific studies were carried out to investigate the complex form of fracture networks and figure out the multi-scale flowing laws of nano/micro poresecomplex fracture networks-wellbore during the development of shale reservoirs by means of horizontal well fracturing.First,hydraulic fractures were induced by means of Brazilian splitting tests.Second,the forms of the hydraulic fractures inside the rock samples were observed by means of X-ray CT scanning to measure the opening of hydraulic fractures.Third,based on the multi-scale unified flowing model,morphological description of fractures and gas flowing mechanism in the matrixecomplex fracture networkewellbore,the productivity equation of single-stage horizontal well fracturing which includes diffusion,slipping and desorption was established.And fourthly,a productivity prediction model of horizontal well multi-stage fracturing in the shale reservoir was established considering the interference between the multi-stage fracturing zones and the pressure drop in the horizontal wellbore.The following results were obtained.First,hydraulic fractures are in the form of a complex network.Second,the measured opening of hydraulic fractures is in the range of 4.25-453 mm,averaging 112 mm.Third,shale gas flowing in different shapes of fracture networks follows different nonlinear flowing laws.Forth,as the fracture density in the strongly stimulated zones rises and the distribution range of the hydraulic fractures in strongly/weakly stimulated zones enlarges,gas production increases gradually.As the interference occurs in the flowing zones of fracture networks between fractured sections,the increasing amplitude of gas production rates decreases.Fifth,when the length of a simulated horizontal well is 1500 m and the half length of a fracture network in the strongly stimulated zone is 100 m,the productivity effect of stage 10 fracturing is the best.Therefore,it is necessary to control fracturing degree reasonably and optimize fracturing parameters,so as to provide a theoretical support for the optimization design of shale gas reservoir fracturing.
文摘To enhance the comprehension of flow characteristics and enrich the well-test theory of slanted wells,this study established a well-test model for a slanted well in a heterogeneous multi-zonal reservoir.The model considered closed boundaries at both the top and bottom,as well as an external boundary with infinite,closed,or constant pressure on the horizontal plane.We took the bi-zonal composite model as an example to carry out concrete analysis.Various contemporary mathematical techniques,including Laplace integral transformation,separation of variables,and eigenfunction methods,were employed to solve the model.The pressure solution in real space was obtained through Duhamel's principle and Stehfest numerical inversion,then analytical curves created,and flow stages were defined for a slanted well in a bi-zonal composite reservoir.In addition,we performed a sensitivity analysis on some parameters affecting the curves.For a tri-zonal composite model,we also plotted the well-test curves and categorized them.Finally,we validated the model through the interpretation of an example well.The results show that the fluid flow of a slanted well in a bi-zonal composite reservoir can be divided into seven main stages,including wellbore storage effect(WSE)stage,skin effect(SE)stage,linear flow(LF)stage,radial flow(RF)stage of the 1st zone,transitional flow(TF)stage from the 1st to the 2nd zone,RF stage of the 2nd zone,and the external boundary response stage.The position of the pressure curve at the SE stage and LF stage decreases as the length and inclination angle increase.Correspondingly,the pressure curve at the RF stage of the 2nd zone and external boundary response stage decreases with increasing mobility ratio.Furthermore,as the radius of the 1st zone increases,the pressure curve at the RF stage of the 1st zone and the TF stage shifts towards the right.The established model and plotted curves provide a theoretical basis for further studies on the flow behavior of slanted wells in composite reservoirs.
文摘目的探讨生境成像(habitat imaging,HI)无创定量可视化前列腺癌(prostate cancer,PCa)分区异质性并预测其危险度的可行性。材料与方法回顾性收集2018年1月至2024年8月在西京医院行多参数磁共振成像(multi-parameteric magnetic resonance imaging,mpMRI)扫描,包括扩散加权成像、体素内非相干运动加权成像和扩散峰度成像,并经根治性前列腺切除术(radical prostatectomy,RP)后病理证实为PCa的147例患者的临床及影像资料,以7∶3分为训练集和测试集。根据RP结果分为移行区(transition zone,TZ)和外周区(peripheral zone,PZ)PCa。整合每体素表观扩散系数(apparent diffusion coefficient,ADC)、灌注分数(perfusion fraction,f)和平均峰度(mean kurtosis,MK)值,划分生境亚区,生成生境地图,从临床、病理、影像多维度比较PZ和TZ PCa间差异。根据2019版国际泌尿病理协会(International Society of Urological Pathology,ISUP)指南,匹配生境地图与RP标本以评估各亚区ISUP分级,将患者分为低危组(ISUP≤2)和高危组(ISUP≥3)。logistic回归分析高危PCa相关特征并构建基于分区的HI(zone-based HI,zHI)-临床影像模型评估危险度,并评估模型效能。结果根据肘部法所示最佳聚类簇数划分3个生境亚区,生境1较生境2、3的ADC、f值更低,MK值更高。相较于TZ,PZ PCa患者临床、病理特征更恶,生境1占比更高。logistic回归分析示解剖分区(OR=3.50,95%CI:1.01~12.09)和生境1占比(OR=3.63,95%CI:1.37~9.62)是高危PCa的独立危险因素(P<0.05)。zHI-临床影像模型评估危险度在训练集和测试集的曲线下面积(area under the curve,AUC)分别为0.889(95%CI:0.822~0.955)和0.883(95%CI:0.740~0.925)。结论本研究多维度验证了PCa分区异质性,并基于解剖分区和HI特征构建模型,对PCa危险度的无创定量可视化预测具有增益效能。
文摘采用由两方程k-ω模式推导得到的k-g模式数值模拟完整飞机构形的跨声速大迎角流场。由于k-g模式具有勿需使用到物面的法向距离、简单的源项和直接的边界条件等特点,可以方便地推广到包含复杂外形的多块网格系统。与雷诺平均N av ier-S tokes方程组的求解方法类似,k-g模式方程也采用显式R unge-K u tta方法进行时间推进,用中心加人工粘性格式进行空间离散。采用相同的方法数值模拟NA SA TN D-712翼身组合体标模迎角为12.5°和26.2°的流场来检验程序的可靠性,与可获得的实验数据进行对比分析并获得满意结果。与此同时,还使用了B a ldw in-Lom ax代数模式以作比较。
