泵站机组运行受多种因素影响,导致泵站运行理论效率与实际效率误差较大。针对泵站机组运行效率精准模拟难题,运用基于高价多项式回归、回归树、多元线性回归、向量机回归、高斯过程回归、神经网络的10个回归算法,建立泵站机组效率模拟...泵站机组运行受多种因素影响,导致泵站运行理论效率与实际效率误差较大。针对泵站机组运行效率精准模拟难题,运用基于高价多项式回归、回归树、多元线性回归、向量机回归、高斯过程回归、神经网络的10个回归算法,建立泵站机组效率模拟模型并开展对比分析,优选出有效的泵站运行效率模拟建模方法。讨论分析采用“上下游水位+流量”代替传统“扬程+流量”开展泵站运行模拟的效果。以南水北调东线邳州站和遂宁二站共8台机组的历史数据开展实例分析,相关实验结果表明:在所有方法中,高斯过程回归(Gaussian process regression,GPR)模型在均方根误差(ERMS)、平均绝对误差(EMA)、均方误差(EMS)、决定系数(R2)和最大个体误差(EMI)指标上综合表现最佳,R2逼近0.95;使用站上、站下水位代替传统的扬程对模型进行训练,所有模型的综合评价指标整体有所改善。综合来看,使用GPR模型并使用上游、下游水位代替扬程进行模拟效率表现最好,以邳州站4号机为例,可将模拟效率的EMA和EMI分别从16.49%和20.40%减少至0.41%和2.30%,研究成果具有一定实际意义,可为我国调水工程泵站经济运行提供有力支撑。展开更多
分析国内外应用SWAT(Soil and Water Assessment Tool)模型模拟流域径流的研究现状,以及流域模型构建,包括流域基础数据和模拟算法的选取、敏感性参数的分析和模型输出的验证.提出模型的应用研究存在3个问题:(1)模型模拟效率受到基础数...分析国内外应用SWAT(Soil and Water Assessment Tool)模型模拟流域径流的研究现状,以及流域模型构建,包括流域基础数据和模拟算法的选取、敏感性参数的分析和模型输出的验证.提出模型的应用研究存在3个问题:(1)模型模拟效率受到基础数据和主观因素的综合影响,而已有的成果参数选取缺乏可比性,大多侧重某个因素如何影响模型效率的研究.(2)流量是各种水文过程综合作用的结果,已有模型验证方法研究多是采用流域出口总径流量模拟效率来检验模型的适用性,这使得模型在水文过程模拟中缺乏可靠性.(3)模型应用研究主要进行土地覆被变化和气候波动的水文效应研究,且多是建立在虚拟情景和简化影响因素基础上.因此,在模型的应用研究上需要综合考虑影响因素,以提高模型模拟效率问题.展开更多
Improved fluid dynamics can enhance the separation efficiency of flotation methods. A Computational Fluid Dynamics simulation using FLUENT was performed to model the fluid environment of a cyclonic-sta- tic micro bubb...Improved fluid dynamics can enhance the separation efficiency of flotation methods. A Computational Fluid Dynamics simulation using FLUENT was performed to model the fluid environment of a cyclonic-sta- tic micro bubble flotation column. The simulation results visually show the interior flow and illustrate mix- ing of the different flows within the apparatus. An analysis of the distribution in velocity and vorticity was used to analyze the separation mechanism and the synergism of the component parts and to strengthen the design of each unit. The conclusions are that axial back mixing and vortexes still exist in the separation unit even in the presence of packing media. The inverted cone structure near the tangential inlet （cone 1 ） within the cyclonic unit is the main reason for this. The cone 1 structure enhances swirling and focuses energy within the inner area of the cone where there are abundant bubbles. As a result slowly floating minerals are forcibly recovered and railings are effectively separated within this unit. However, cone 1 also reduces the vorticity downstream from it, which reduces the efficiency of railings separation within this part. Therefore, the design of cone 1 should be based on the principles of lessening disturbances to the column unit while strengthening the separation effect of the cyclonic unit. Also, the axial distance between the paired cyclonic structures at the bottom of the column （cone 2） and cone 1 poses tough requirements because of an interaction between separation of the middlings and railings.展开更多
In limited feedback-based CloudRAN(C-RAN) systems,the inter-cluster and intra-cluster interference together with the quantification error can seriously deteriorates the system spectral efficiency.We,in this paper,prop...In limited feedback-based CloudRAN(C-RAN) systems,the inter-cluster and intra-cluster interference together with the quantification error can seriously deteriorates the system spectral efficiency.We,in this paper,propose an efficient three-phase framework and corresponding algorithms for dealing with this problem.Firstly,a greedy scheduling algorithm based on the lower bound of the ergodic rate is performed for generating an elementary cluster in the first phase.And then the elementary cluster is divided into many small clusters according to the following proposed algorithms based on the short term instantaneous information in the second phase.In the end,based on the limited feedback two zero-forcing(ZF) precoding strategies are adopted for reducing the intra-cluster interference in the third phase.The provided Monte Carlo simulations show the effectiveness of our proposed algorithms in the respect of system spectral efficiency and average user rate.展开更多
Coalbed methane(CBM) commercial development requires choosing the arrangement of the wells.This should be done by considering the corresponding input-output(investment-profit) efficiencies.Simulations were obtained fr...Coalbed methane(CBM) commercial development requires choosing the arrangement of the wells.This should be done by considering the corresponding input-output(investment-profit) efficiencies.Simulations were obtained from the computer modeling group(CMG) given the reservoir conditions of the Panzhuang block in the southern part of the Qinshui Basin.This is a demonstration region for CBM development located in Shanxi province of northern China.The sensitivity of gas production from a single vertical well to the primary reservoir parameters was estimated first.Then multi-well gas production from three different well patterns was simulated to estimate the most appropriate well spacing.Combining the investment requirements then gave investment-profit efficiencies for these well patterns.A data envelopment analysis(DEA) model was used to optimize the efficiency.The results show that the permeability,the reservoir pressure,and the gas content have an evident impact on single well gas production.The desorption time has little or no affect on production.The equilateral triangular well pattern(ETWP) in a 400 m well spacing is,for multi-well development,the optimal pattern.It has a better input-output ratio,a longer stable yield time,and provides for greater CBM recovery than does either the rectangular well pattern(RWP) or the five point well pattern(FPWP).展开更多
Counter beam lighting was introduced as well as transverse symmetrical lighting and longitudinal symmetrical lighting.Simulation experiments were carried out by using DIAlux lighting software for the above three light...Counter beam lighting was introduced as well as transverse symmetrical lighting and longitudinal symmetrical lighting.Simulation experiments were carried out by using DIAlux lighting software for the above three lighting methods.The results show that counter beam lighting is more reasonable to be adopted in the tunnel entrance zone because its threshold increment of disability glare is greater.Counter beam lighting can improve the background luminance of the obstacles and lighting efficiency compared with transverse symmetrical lighting and longitudinal symmetrical lighting.Therefore,tunnel lighting energy-saving can be achieved by reducing the road luminance demands and luminaries power.Longitudinal symmetrical lighting is conducive to the large luminaries spacing in the tunnel internal zone;so power consumption can be reduced by decreasing the number of luminaries used.Tunnel walls are unsuitable to pave with smooth or bright material.Installation height of the luminaries has less effect on counter beam lighting.展开更多
In this paper, we present a comprehensive numerical simulation of a point wave absorber in deep water. Analyses are performed in both the frequency and time domains. The converter is a two-body floating-point absorber...In this paper, we present a comprehensive numerical simulation of a point wave absorber in deep water. Analyses are performed in both the frequency and time domains. The converter is a two-body floating-point absorber （FPA） with one degree of freedom in the heave direction. Its two parts are connected by a linear mass-spring-damper system. The commercial ANSYS-AQWA software used in this study performs well in considering validations. The velocity potential is obtained by assuming incompressible and irrotational flow. As such, we investigated the effects of wave characteristics on energy conversion and device efficiency, including wave height and wave period, as well as the device diameter, draft, geometry, and damping coefficient. To validate the model, we compared our numerical results with those from similar experiments. Our study results can clearly help to maximize the converter＇s efficiency when considering specific conditions.展开更多
Massive multiple input and multiple output(MIMO) is a key technology of the fifth generation(5 G) wireless communication systems, which brings various advantages, such as high spectral efficiency and energy efficiency...Massive multiple input and multiple output(MIMO) is a key technology of the fifth generation(5 G) wireless communication systems, which brings various advantages, such as high spectral efficiency and energy efficiency. In MIMO system, spatial modulation(SM) has recently emerged as a new transmission method. In this paper, in order to improve the security in SM-MIMO, a physical layer encryption approach named chaotic antenna-index three-dimensional modulation and constellation points rotated(CATMCPR) encryption scheme is proposed, which utilizes the chaotic theory and spatial modulation techniques. The conventional physical-layer encryption in SM-MIMO suffers from spectral efficiency(SE) performance degradation and usually needs a preshared key, prior channel state information(CSI) or excess jamming power. By contrast, we show that the CATMCPR scheme can not only achieve securely communication but also improve above drawbacks. We evaluate the performances of the proposed scheme by an analysis and computer simulations.展开更多
In the present work, computational simulations was made using ANSYS CFX to predict the improvements in film cooling performance with dual trench. Dual-trench confguradon consists of two trenches together, one wider tr...In the present work, computational simulations was made using ANSYS CFX to predict the improvements in film cooling performance with dual trench. Dual-trench confguradon consists of two trenches together, one wider trench and the other is narrow trench that extruded from the wider one. Several blowing ratios in the range （0.5：5） were investigated. The pitch-to-diameter ratio of 2.775 is used. By using the dual trench configuration, the coolant jet impacted the trench wall two times allowing increasing the spreading of coolant laterally in the trench, reducing jet velocity and jet completely covered on the surface. The results indicate that this configuration increased adiabatic effectiveness as blowing ratio increased. The spatially averaged adiabatic effectiveness reached 57.6% for at M= 2. No observed film blow-off at all blowing ratios. The adiabatic film effectiveness of dual trench case outperformed the narrow trench case, laidback fan-shaped hole, fan-shaped hole and cylinder hole at different blowing ratios.展开更多
文摘泵站机组运行受多种因素影响,导致泵站运行理论效率与实际效率误差较大。针对泵站机组运行效率精准模拟难题,运用基于高价多项式回归、回归树、多元线性回归、向量机回归、高斯过程回归、神经网络的10个回归算法,建立泵站机组效率模拟模型并开展对比分析,优选出有效的泵站运行效率模拟建模方法。讨论分析采用“上下游水位+流量”代替传统“扬程+流量”开展泵站运行模拟的效果。以南水北调东线邳州站和遂宁二站共8台机组的历史数据开展实例分析,相关实验结果表明:在所有方法中,高斯过程回归(Gaussian process regression,GPR)模型在均方根误差(ERMS)、平均绝对误差(EMA)、均方误差(EMS)、决定系数(R2)和最大个体误差(EMI)指标上综合表现最佳,R2逼近0.95;使用站上、站下水位代替传统的扬程对模型进行训练,所有模型的综合评价指标整体有所改善。综合来看,使用GPR模型并使用上游、下游水位代替扬程进行模拟效率表现最好,以邳州站4号机为例,可将模拟效率的EMA和EMI分别从16.49%和20.40%减少至0.41%和2.30%,研究成果具有一定实际意义,可为我国调水工程泵站经济运行提供有力支撑。
文摘分析国内外应用SWAT(Soil and Water Assessment Tool)模型模拟流域径流的研究现状,以及流域模型构建,包括流域基础数据和模拟算法的选取、敏感性参数的分析和模型输出的验证.提出模型的应用研究存在3个问题:(1)模型模拟效率受到基础数据和主观因素的综合影响,而已有的成果参数选取缺乏可比性,大多侧重某个因素如何影响模型效率的研究.(2)流量是各种水文过程综合作用的结果,已有模型验证方法研究多是采用流域出口总径流量模拟效率来检验模型的适用性,这使得模型在水文过程模拟中缺乏可靠性.(3)模型应用研究主要进行土地覆被变化和气候波动的水文效应研究,且多是建立在虚拟情景和简化影响因素基础上.因此,在模型的应用研究上需要综合考虑影响因素,以提高模型模拟效率问题.
基金supported by the National Natural Science Foundation of China (No. 51074157)the Foundation of China University of Mining and Technology (No. 2011QNA08)
文摘Improved fluid dynamics can enhance the separation efficiency of flotation methods. A Computational Fluid Dynamics simulation using FLUENT was performed to model the fluid environment of a cyclonic-sta- tic micro bubble flotation column. The simulation results visually show the interior flow and illustrate mix- ing of the different flows within the apparatus. An analysis of the distribution in velocity and vorticity was used to analyze the separation mechanism and the synergism of the component parts and to strengthen the design of each unit. The conclusions are that axial back mixing and vortexes still exist in the separation unit even in the presence of packing media. The inverted cone structure near the tangential inlet （cone 1 ） within the cyclonic unit is the main reason for this. The cone 1 structure enhances swirling and focuses energy within the inner area of the cone where there are abundant bubbles. As a result slowly floating minerals are forcibly recovered and railings are effectively separated within this unit. However, cone 1 also reduces the vorticity downstream from it, which reduces the efficiency of railings separation within this part. Therefore, the design of cone 1 should be based on the principles of lessening disturbances to the column unit while strengthening the separation effect of the cyclonic unit. Also, the axial distance between the paired cyclonic structures at the bottom of the column （cone 2） and cone 1 poses tough requirements because of an interaction between separation of the middlings and railings.
基金supported by the National Natural Science Foundation of China(NSFC) under Grant(No. 61461136001)
文摘In limited feedback-based CloudRAN(C-RAN) systems,the inter-cluster and intra-cluster interference together with the quantification error can seriously deteriorates the system spectral efficiency.We,in this paper,propose an efficient three-phase framework and corresponding algorithms for dealing with this problem.Firstly,a greedy scheduling algorithm based on the lower bound of the ergodic rate is performed for generating an elementary cluster in the first phase.And then the elementary cluster is divided into many small clusters according to the following proposed algorithms based on the short term instantaneous information in the second phase.In the end,based on the limited feedback two zero-forcing(ZF) precoding strategies are adopted for reducing the intra-cluster interference in the third phase.The provided Monte Carlo simulations show the effectiveness of our proposed algorithms in the respect of system spectral efficiency and average user rate.
基金supported by the National Natural Science Foundation of China (No. 40972207)the National Science and Technology Major Projects (No. 2011ZX05034-005)the PAPD of Jiangsu Higher Education Institutions
文摘Coalbed methane(CBM) commercial development requires choosing the arrangement of the wells.This should be done by considering the corresponding input-output(investment-profit) efficiencies.Simulations were obtained from the computer modeling group(CMG) given the reservoir conditions of the Panzhuang block in the southern part of the Qinshui Basin.This is a demonstration region for CBM development located in Shanxi province of northern China.The sensitivity of gas production from a single vertical well to the primary reservoir parameters was estimated first.Then multi-well gas production from three different well patterns was simulated to estimate the most appropriate well spacing.Combining the investment requirements then gave investment-profit efficiencies for these well patterns.A data envelopment analysis(DEA) model was used to optimize the efficiency.The results show that the permeability,the reservoir pressure,and the gas content have an evident impact on single well gas production.The desorption time has little or no affect on production.The equilateral triangular well pattern(ETWP) in a 400 m well spacing is,for multi-well development,the optimal pattern.It has a better input-output ratio,a longer stable yield time,and provides for greater CBM recovery than does either the rectangular well pattern(RWP) or the five point well pattern(FPWP).
基金Funded by Key Laboratory of Ministry of Education for Conveyance and Equipment,East China Jiaotong University(No. 09JD09)
文摘Counter beam lighting was introduced as well as transverse symmetrical lighting and longitudinal symmetrical lighting.Simulation experiments were carried out by using DIAlux lighting software for the above three lighting methods.The results show that counter beam lighting is more reasonable to be adopted in the tunnel entrance zone because its threshold increment of disability glare is greater.Counter beam lighting can improve the background luminance of the obstacles and lighting efficiency compared with transverse symmetrical lighting and longitudinal symmetrical lighting.Therefore,tunnel lighting energy-saving can be achieved by reducing the road luminance demands and luminaries power.Longitudinal symmetrical lighting is conducive to the large luminaries spacing in the tunnel internal zone;so power consumption can be reduced by decreasing the number of luminaries used.Tunnel walls are unsuitable to pave with smooth or bright material.Installation height of the luminaries has less effect on counter beam lighting.
文摘In this paper, we present a comprehensive numerical simulation of a point wave absorber in deep water. Analyses are performed in both the frequency and time domains. The converter is a two-body floating-point absorber （FPA） with one degree of freedom in the heave direction. Its two parts are connected by a linear mass-spring-damper system. The commercial ANSYS-AQWA software used in this study performs well in considering validations. The velocity potential is obtained by assuming incompressible and irrotational flow. As such, we investigated the effects of wave characteristics on energy conversion and device efficiency, including wave height and wave period, as well as the device diameter, draft, geometry, and damping coefficient. To validate the model, we compared our numerical results with those from similar experiments. Our study results can clearly help to maximize the converter＇s efficiency when considering specific conditions.
基金supported in part by the National Natural Science Foundation of China under Grant 61502518,61372098 and 61702536
文摘Massive multiple input and multiple output(MIMO) is a key technology of the fifth generation(5 G) wireless communication systems, which brings various advantages, such as high spectral efficiency and energy efficiency. In MIMO system, spatial modulation(SM) has recently emerged as a new transmission method. In this paper, in order to improve the security in SM-MIMO, a physical layer encryption approach named chaotic antenna-index three-dimensional modulation and constellation points rotated(CATMCPR) encryption scheme is proposed, which utilizes the chaotic theory and spatial modulation techniques. The conventional physical-layer encryption in SM-MIMO suffers from spectral efficiency(SE) performance degradation and usually needs a preshared key, prior channel state information(CSI) or excess jamming power. By contrast, we show that the CATMCPR scheme can not only achieve securely communication but also improve above drawbacks. We evaluate the performances of the proposed scheme by an analysis and computer simulations.
基金Supprted by Harbin Engineering University Scholarship under Grant No. 20100903D01
文摘In the present work, computational simulations was made using ANSYS CFX to predict the improvements in film cooling performance with dual trench. Dual-trench confguradon consists of two trenches together, one wider trench and the other is narrow trench that extruded from the wider one. Several blowing ratios in the range （0.5：5） were investigated. The pitch-to-diameter ratio of 2.775 is used. By using the dual trench configuration, the coolant jet impacted the trench wall two times allowing increasing the spreading of coolant laterally in the trench, reducing jet velocity and jet completely covered on the surface. The results indicate that this configuration increased adiabatic effectiveness as blowing ratio increased. The spatially averaged adiabatic effectiveness reached 57.6% for at M= 2. No observed film blow-off at all blowing ratios. The adiabatic film effectiveness of dual trench case outperformed the narrow trench case, laidback fan-shaped hole, fan-shaped hole and cylinder hole at different blowing ratios.
