The current work seeks to examine numerical heat transfer by using a complicated channel with a trapezoid shape hanging in the channel.This channel demonstrates two-dimensional laminar flow,forced convective flow,and ...The current work seeks to examine numerical heat transfer by using a complicated channel with a trapezoid shape hanging in the channel.This channel demonstrates two-dimensional laminar flow,forced convective flow,and incompressible flow.To explore the behavior of heat transfer in complex channels,several parameters,such as the constant Prandtl number(Pr=6.9),volume fraction(ϕ)equal to(0.02 to 0.04),Cauchy number(Ca)equal to(10^(-4) to 10^(-8)),and Reynolds number equal to(60 to 160)were utilized.At the complex channel,different elastic walls are used in different locations,with case A being devoid of an elastic wall,cases B and C each having three elastic walls before and after the trapezoid shape,respectively,and case D having six elastic walls.The geometry of a complicated channel with varying L2/H2 and B/H2 ratios is investigated.The trouble was solved using the FEM with the ALE technique.The results showed that the best case with an elastic wall is reached for B/H2=0.8 and L2/H2=3.When compared to the channel without a flexible wall in case A,the highest reading for Nusselt was recorded at case C with a percentage of 34.5 percent,followed by case B(31.4 percent)and then case D(21.5 percent).It also has the highest Nusselt number reading at Ca=10^(-4) and Re=160,or about 6.4 when compared to Ca=10^(-5) and Ca=10^(-8).In case A,ΔP increases as the Re grows;however,in cases B and C,the ΔP reduces as the Re increases,but in case D,the ΔP increases with increasing Re.展开更多
The dynamic relationship between field management and reservoir characterization has often been a puzzle,especially in complex deepwater channel systems.Reservoir management and infill drilling success cases were ofte...The dynamic relationship between field management and reservoir characterization has often been a puzzle,especially in complex deepwater channel systems.Reservoir management and infill drilling success cases were often due to improved understanding of deepwater depositional systems and geological controls on channel architecture and the general distribution of individual rock facies.For confined to weakly-confined slope channel complexes,some controls on the degree of channel avulsion and aggradation are the interplay between flow hydraulics,sediment calibre,depositional gradient,and the interaction of the flow with underlying substrate.This work aims at documenting the stratigraphic characterization of a Miocene deepwater channel system in a brownfield with focus on the historical evolution of the framework interpretation as well as applications of the recent updates in field management.The initial stratigraphic model(2005)was done using the layer cake concept with minimal incision,continuous shales and limited vertical connectivity based on observations from available seismic data(pre-baseline survey acquisition)and limited well control.This was modified in 2009 following acquisition of a 4D Monitor 1 seismic volume and 3 years production data from 20 wells to a more erosive model with compensationally stacked channel complexes of similar width.With new 4D Monitor 2 acquired in 2014,broadband processed seismic data in 2020,a total of 36 wells and 11 years of production,an updated framework has recently been built.In the new framework,two key fairways namely the Upper and the Lower Fairway were delineated,each comprising of 8 and 6 channel complexes,respectively.A conceptual basin-fill sequence was utilized,as well as a genetic classification of the channel complexes into erosional-confined systems,meandering systems,and levee-confined channel systems.The cut-and-fill behaviors of the individual complexes have been tied to changes in depositional gradient,sediment sand vs mud ratio,interaction of the flow with the substrate,and this has impacted the degree of channel amalgamation,avulsion and the degree of preservation of both internal and external levees.At flow unit scale,potential inter,and intra-reservoir connection pathways and compartments defined through integrated use of excess pressures,geobody attributes,well production and 4D data,have been very helpful in defining reservoir connection windows,injector-producer connectivity,and channel compartments.The implication is that this exercise or study has provided renewed insights into infill drill-well opportunities,well production performance as well as overall field management strategy.展开更多
The combination of both 4,4′-bipyridine(4,4′-bipy) and dihydrogen phosphate anion ligands with copper(Ⅱ) results in the formation of a novel layered compound Cu(4,4′-bipy)_2(H_2PO_4)_2(H_2O)_2. The crystal structu...The combination of both 4,4′-bipyridine(4,4′-bipy) and dihydrogen phosphate anion ligands with copper(Ⅱ) results in the formation of a novel layered compound Cu(4,4′-bipy)_2(H_2PO_4)_2(H_2O)_2. The crystal structure comprises discrete neutral Cu(4,4′-bipy)_2(H_2PO_4)_2(H_2O)_2 units. The copper atom,located on the crystallographic twofold axis,is coordinated with two nitrogen atoms of terminal 4,4′-bipy ligands and two water molecules at the equatorial positions,and two dihydrogen phosphate oxygen atoms at the axial positions,forming an elongated octahedron. The complex is a two-dimensional distorted rhomboidal network possessing two kinds of rhomboids with dimensions of ca . 1.6792 nm×0.3203 nm and 1.2778 nm×0.3198 nm,respectively. The two-dimensional networks are stacked parallelly on each other along c -axis to give an extended three-dimensional channel network with an interlayer distance of ca . 0.5030 nm. Crystal data: triclinic,space group P -_1,a =1.0253(2) nm,b =1.4501(3) nm,c =0.79715(16) nm, α =97.91(3)°,β = 90.99(3)° ,γ =85.54(3)°,V =1.1703(4) nm 3,Z =2,R =0.0892,wR =0.2451.展开更多
In order to study the bearing capacity and stability behavior of cold-formed steel flexural members with complicated sections,a total of 12 specimens divided into 6 groups were tested,including 3 groups of pure bendin...In order to study the bearing capacity and stability behavior of cold-formed steel flexural members with complicated sections,a total of 12 specimens divided into 6 groups were tested,including 3 groups of pure bending tests and non-pure bending tests each.There were three types of sections considered in this investigation,including channels with complex edge stiffeners(called B1-section),Σsection with complex edge stiffeners(called B2-section),and channels with complex edge stiffeners and V-type web stiffeners(called B3-section).Local buckling,distortional buckling and interaction buckling between them were observed in tests.The experimental results indicate that the bending strengths of B2-section specimens were the largest of these three types of specimens under the same conditions.It is found that the bending strength of B2-section specimens was increased by 6.47%for pure bending state and 8.12%for non-pure bending state,compared with that of B1-section specimens.Bending strength of B3-section specimens was almost the same with that of B1-section specimens under pure bending,but a little smaller than that of B1-section under non-pure bending state.It is also shown that B2-section specimens have better plastic deformation behavior than the other two sections.In addition,a non-linear finite element model was presented and verified against tests.The finite element analysis results agree well with experimental bending strength and failure modes.展开更多
A 3rd-order Butterworth active-RC complex band-pass filter was presented for Zig Bee(IEEE802.15.4) transceiver applications. The filter adopted cascaded complex pole stages to realize the 3 MHz bandwidth with a centre...A 3rd-order Butterworth active-RC complex band-pass filter was presented for Zig Bee(IEEE802.15.4) transceiver applications. The filter adopted cascaded complex pole stages to realize the 3 MHz bandwidth with a centre frequency of 2 MHz which was required by the Zig Bee transceiver applications. An automatic frequency tuning scheme was also designed to accommodate the performance deterioration due to the process, voltage and temperature(PVT) variations. The whole filter is implemented in a 0.18 μm standard process and occupies an area of 1.3 mm×0.6 mm. The current dissipation is 1.2 m A from a 1.8 V single power supply. Measurement results show that the image rejection ratio(IRR) of the filter is 24.1 d B with a pass-band ripple less than 0.3 d B. The adjacent channel rejection is 29.8 d B@7 MHz and alternate channel rejection 47.5 d B@12 MHz, respectively.展开更多
The Laramie River after flowing in a north direction through southeast Wyoming’s Laramie Basin abruptly turns in an east direction to flow across the north-to-south oriented Laramie Range in a bedrock-walled canyon a...The Laramie River after flowing in a north direction through southeast Wyoming’s Laramie Basin abruptly turns in an east direction to flow across the north-to-south oriented Laramie Range in a bedrock-walled canyon and eventually reaches the lower elevation Great Plains and southeast-oriented North Platte River. The North Laramie River, Bluegrass Creek, and North Sybille/Sybille Creek also flow from the Laramie Basin in separate bedrock-walled valleys into the Laramie Range before eventually joining the Laramie River. Bedrock-walled through valleys link the various Laramie Range stream and river crossing valleys and detailed topographic maps were used to determine how this anastomosing bedrock-walled canyon complex and the large escarpment-surrounded Goshen Hole basin (located just to the east of the anastomosing canyon complex) originated. Map evidence shows multiple streams of water must have diverged in the Laramie Basin from the north-oriented Laramie River to enter the Laramie Range before converging in or east of the Laramie Range and also shows how present day through valleys enabled diverging and converging streams of water to cross the Laramie Range. The anastomosing bedrock-walled valley complex studied here extends from north of the North Laramie River valley to south of the North Sybille/Sybille Creek valley. Large volumes of water flowing from the Laramie Basin to the Great Plains are interpreted to have eroded the anastomosing canyon complex and the “downstream” Goshen Hole escarpment-surrounded basin. Headward erosion of the north-oriented Sybille and Chugwater Creek valleys across large sheets of east-oriented water are interpreted to have left the Goshen Hole escarpment-surrounded basin as a large abandoned headcut. A water source was not determined, although a continental ice sheet that deeply eroded and warped the North American continent is considered to be a possible source.展开更多
In this study, field hydraulic experiments were carried out on typical mountain rivers in the Taizicheng River Basin. The surface water flow velocity, water depth, river width and other data of the Taizicheng River we...In this study, field hydraulic experiments were carried out on typical mountain rivers in the Taizicheng River Basin. The surface water flow velocity, water depth, river width and other data of the Taizicheng River were measured regularly and continuously. The change of Manning coefficient along the river in the mountain complex was studied, and the relationship between Manning coefficient N and relevant hydraulic parameters was analyzed. The results show that: (1) The value of N in the upper reaches of the river is higher than that in the middle and lower reaches of the river, and there is no significant difference in the value of N in different river courses at the junction of main and tributaries;(2) The value of N and its change trend are restricted by hydrological conditions;(3) n has a good power function relationship with water depth H and Reynolds number Re, and a good logarithmic function relationship with Froude number Fr. The ratio of Manning coefficient to water depth n/h and Re has a negative power function relationship;(4) Under the significance level of p<0.01, the goodness-of-fit R2 of the relationships among n-h, n-Re and n-Fr all reached above 0.82, which can better reflect the influence of n on the water flow state. The research results can provide reference for the construction of ecological treatment project of mountain complex river.展开更多
无人机由于其灵活部署、广泛覆盖和高移动性等特点在6G无线通信网络发展中至关重要,同时也为信道研究带来了挑战。提出了一种适用于6G无人机通信网络的多输入多输出(Multiple-Input Multiple-Output,MIMO)空地无线通信场景的信道模型。...无人机由于其灵活部署、广泛覆盖和高移动性等特点在6G无线通信网络发展中至关重要,同时也为信道研究带来了挑战。提出了一种适用于6G无人机通信网络的多输入多输出(Multiple-Input Multiple-Output,MIMO)空地无线通信场景的信道模型。实际场景中无人机发射机与地面移动用户接收机之间的直接传播链路经常被树木和建筑物阻断,为了解决这一问题,通过引入双智能反射表面(Intelligent Reflecting Surfaces,IRS)技术来实现信号传输,形成双IRS、单IRS以及非视距(Non Line of Sight,NLOS)路径的传播链路。研究了这些链路的复杂信道冲激响应,考虑了多径效应的影响并据此推导出了完整的信道矩阵,分析了该信道模型在不同模型参数下的统计特性。基于这些理论推导,进一步研究了双IRS辅助空对地通信信道模型的传播特性。仿真结果表明,相较于单IRS配置,双IRS在提升系统性能方面具有显著优势,为进一步优化和设计基于IRS的空对地无线通信系统提供了有价值的参考。展开更多
为了保证水下设备的长期稳定通信,提出了一种基于改进的快速边缘似然最大化的稀疏贝叶斯学习(sparse Bayesian learning based on improved fast marginal likelihood maximization, IFM-SBL)算法,对水声信道进行低复杂度、高性能的估...为了保证水下设备的长期稳定通信,提出了一种基于改进的快速边缘似然最大化的稀疏贝叶斯学习(sparse Bayesian learning based on improved fast marginal likelihood maximization, IFM-SBL)算法,对水声信道进行低复杂度、高性能的估计。特别是在低信噪比情况下,通过阈值去噪和离散傅里叶变换降噪,可以进一步提升算法的性能。仿真和海试结果表明,所提的IFM-SBL信道估计后的输出误码率与基于期望最大化的稀疏贝叶斯学习(sparse Bayesian learning based on expectation maximization, EM-SBL)算法相似,且验证了算法在低信噪比和快慢时变信道中都具有良好的鲁棒性。在运行速度方面,FM-SBL算法与IFM-SBL算法比EM-SBL算法提高了约90%,大大减少了信道估计时间。展开更多
文摘The current work seeks to examine numerical heat transfer by using a complicated channel with a trapezoid shape hanging in the channel.This channel demonstrates two-dimensional laminar flow,forced convective flow,and incompressible flow.To explore the behavior of heat transfer in complex channels,several parameters,such as the constant Prandtl number(Pr=6.9),volume fraction(ϕ)equal to(0.02 to 0.04),Cauchy number(Ca)equal to(10^(-4) to 10^(-8)),and Reynolds number equal to(60 to 160)were utilized.At the complex channel,different elastic walls are used in different locations,with case A being devoid of an elastic wall,cases B and C each having three elastic walls before and after the trapezoid shape,respectively,and case D having six elastic walls.The geometry of a complicated channel with varying L2/H2 and B/H2 ratios is investigated.The trouble was solved using the FEM with the ALE technique.The results showed that the best case with an elastic wall is reached for B/H2=0.8 and L2/H2=3.When compared to the channel without a flexible wall in case A,the highest reading for Nusselt was recorded at case C with a percentage of 34.5 percent,followed by case B(31.4 percent)and then case D(21.5 percent).It also has the highest Nusselt number reading at Ca=10^(-4) and Re=160,or about 6.4 when compared to Ca=10^(-5) and Ca=10^(-8).In case A,ΔP increases as the Re grows;however,in cases B and C,the ΔP reduces as the Re increases,but in case D,the ΔP increases with increasing Re.
文摘The dynamic relationship between field management and reservoir characterization has often been a puzzle,especially in complex deepwater channel systems.Reservoir management and infill drilling success cases were often due to improved understanding of deepwater depositional systems and geological controls on channel architecture and the general distribution of individual rock facies.For confined to weakly-confined slope channel complexes,some controls on the degree of channel avulsion and aggradation are the interplay between flow hydraulics,sediment calibre,depositional gradient,and the interaction of the flow with underlying substrate.This work aims at documenting the stratigraphic characterization of a Miocene deepwater channel system in a brownfield with focus on the historical evolution of the framework interpretation as well as applications of the recent updates in field management.The initial stratigraphic model(2005)was done using the layer cake concept with minimal incision,continuous shales and limited vertical connectivity based on observations from available seismic data(pre-baseline survey acquisition)and limited well control.This was modified in 2009 following acquisition of a 4D Monitor 1 seismic volume and 3 years production data from 20 wells to a more erosive model with compensationally stacked channel complexes of similar width.With new 4D Monitor 2 acquired in 2014,broadband processed seismic data in 2020,a total of 36 wells and 11 years of production,an updated framework has recently been built.In the new framework,two key fairways namely the Upper and the Lower Fairway were delineated,each comprising of 8 and 6 channel complexes,respectively.A conceptual basin-fill sequence was utilized,as well as a genetic classification of the channel complexes into erosional-confined systems,meandering systems,and levee-confined channel systems.The cut-and-fill behaviors of the individual complexes have been tied to changes in depositional gradient,sediment sand vs mud ratio,interaction of the flow with the substrate,and this has impacted the degree of channel amalgamation,avulsion and the degree of preservation of both internal and external levees.At flow unit scale,potential inter,and intra-reservoir connection pathways and compartments defined through integrated use of excess pressures,geobody attributes,well production and 4D data,have been very helpful in defining reservoir connection windows,injector-producer connectivity,and channel compartments.The implication is that this exercise or study has provided renewed insights into infill drill-well opportunities,well production performance as well as overall field management strategy.
文摘The combination of both 4,4′-bipyridine(4,4′-bipy) and dihydrogen phosphate anion ligands with copper(Ⅱ) results in the formation of a novel layered compound Cu(4,4′-bipy)_2(H_2PO_4)_2(H_2O)_2. The crystal structure comprises discrete neutral Cu(4,4′-bipy)_2(H_2PO_4)_2(H_2O)_2 units. The copper atom,located on the crystallographic twofold axis,is coordinated with two nitrogen atoms of terminal 4,4′-bipy ligands and two water molecules at the equatorial positions,and two dihydrogen phosphate oxygen atoms at the axial positions,forming an elongated octahedron. The complex is a two-dimensional distorted rhomboidal network possessing two kinds of rhomboids with dimensions of ca . 1.6792 nm×0.3203 nm and 1.2778 nm×0.3198 nm,respectively. The two-dimensional networks are stacked parallelly on each other along c -axis to give an extended three-dimensional channel network with an interlayer distance of ca . 0.5030 nm. Crystal data: triclinic,space group P -_1,a =1.0253(2) nm,b =1.4501(3) nm,c =0.79715(16) nm, α =97.91(3)°,β = 90.99(3)° ,γ =85.54(3)°,V =1.1703(4) nm 3,Z =2,R =0.0892,wR =0.2451.
基金Project(51008200)supported by the National Natural Science Foundation of ChinaProject(2015020575)supported by Natural Science Foundation of Liaoning Province,ChinaProject(F16-205-1-14)supported by Science and Technology Program of Shenyang City,China
文摘In order to study the bearing capacity and stability behavior of cold-formed steel flexural members with complicated sections,a total of 12 specimens divided into 6 groups were tested,including 3 groups of pure bending tests and non-pure bending tests each.There were three types of sections considered in this investigation,including channels with complex edge stiffeners(called B1-section),Σsection with complex edge stiffeners(called B2-section),and channels with complex edge stiffeners and V-type web stiffeners(called B3-section).Local buckling,distortional buckling and interaction buckling between them were observed in tests.The experimental results indicate that the bending strengths of B2-section specimens were the largest of these three types of specimens under the same conditions.It is found that the bending strength of B2-section specimens was increased by 6.47%for pure bending state and 8.12%for non-pure bending state,compared with that of B1-section specimens.Bending strength of B3-section specimens was almost the same with that of B1-section specimens under pure bending,but a little smaller than that of B1-section under non-pure bending state.It is also shown that B2-section specimens have better plastic deformation behavior than the other two sections.In addition,a non-linear finite element model was presented and verified against tests.The finite element analysis results agree well with experimental bending strength and failure modes.
基金Projects(61334003,61274026) supported by the National Natural Science Foundation of ChinaProject(K5051225006) supported by the Fundamental Research Fund for the Central Universities,China
文摘A 3rd-order Butterworth active-RC complex band-pass filter was presented for Zig Bee(IEEE802.15.4) transceiver applications. The filter adopted cascaded complex pole stages to realize the 3 MHz bandwidth with a centre frequency of 2 MHz which was required by the Zig Bee transceiver applications. An automatic frequency tuning scheme was also designed to accommodate the performance deterioration due to the process, voltage and temperature(PVT) variations. The whole filter is implemented in a 0.18 μm standard process and occupies an area of 1.3 mm×0.6 mm. The current dissipation is 1.2 m A from a 1.8 V single power supply. Measurement results show that the image rejection ratio(IRR) of the filter is 24.1 d B with a pass-band ripple less than 0.3 d B. The adjacent channel rejection is 29.8 d B@7 MHz and alternate channel rejection 47.5 d B@12 MHz, respectively.
文摘The Laramie River after flowing in a north direction through southeast Wyoming’s Laramie Basin abruptly turns in an east direction to flow across the north-to-south oriented Laramie Range in a bedrock-walled canyon and eventually reaches the lower elevation Great Plains and southeast-oriented North Platte River. The North Laramie River, Bluegrass Creek, and North Sybille/Sybille Creek also flow from the Laramie Basin in separate bedrock-walled valleys into the Laramie Range before eventually joining the Laramie River. Bedrock-walled through valleys link the various Laramie Range stream and river crossing valleys and detailed topographic maps were used to determine how this anastomosing bedrock-walled canyon complex and the large escarpment-surrounded Goshen Hole basin (located just to the east of the anastomosing canyon complex) originated. Map evidence shows multiple streams of water must have diverged in the Laramie Basin from the north-oriented Laramie River to enter the Laramie Range before converging in or east of the Laramie Range and also shows how present day through valleys enabled diverging and converging streams of water to cross the Laramie Range. The anastomosing bedrock-walled valley complex studied here extends from north of the North Laramie River valley to south of the North Sybille/Sybille Creek valley. Large volumes of water flowing from the Laramie Basin to the Great Plains are interpreted to have eroded the anastomosing canyon complex and the “downstream” Goshen Hole escarpment-surrounded basin. Headward erosion of the north-oriented Sybille and Chugwater Creek valleys across large sheets of east-oriented water are interpreted to have left the Goshen Hole escarpment-surrounded basin as a large abandoned headcut. A water source was not determined, although a continental ice sheet that deeply eroded and warped the North American continent is considered to be a possible source.
文摘In this study, field hydraulic experiments were carried out on typical mountain rivers in the Taizicheng River Basin. The surface water flow velocity, water depth, river width and other data of the Taizicheng River were measured regularly and continuously. The change of Manning coefficient along the river in the mountain complex was studied, and the relationship between Manning coefficient N and relevant hydraulic parameters was analyzed. The results show that: (1) The value of N in the upper reaches of the river is higher than that in the middle and lower reaches of the river, and there is no significant difference in the value of N in different river courses at the junction of main and tributaries;(2) The value of N and its change trend are restricted by hydrological conditions;(3) n has a good power function relationship with water depth H and Reynolds number Re, and a good logarithmic function relationship with Froude number Fr. The ratio of Manning coefficient to water depth n/h and Re has a negative power function relationship;(4) Under the significance level of p<0.01, the goodness-of-fit R2 of the relationships among n-h, n-Re and n-Fr all reached above 0.82, which can better reflect the influence of n on the water flow state. The research results can provide reference for the construction of ecological treatment project of mountain complex river.
文摘无人机由于其灵活部署、广泛覆盖和高移动性等特点在6G无线通信网络发展中至关重要,同时也为信道研究带来了挑战。提出了一种适用于6G无人机通信网络的多输入多输出(Multiple-Input Multiple-Output,MIMO)空地无线通信场景的信道模型。实际场景中无人机发射机与地面移动用户接收机之间的直接传播链路经常被树木和建筑物阻断,为了解决这一问题,通过引入双智能反射表面(Intelligent Reflecting Surfaces,IRS)技术来实现信号传输,形成双IRS、单IRS以及非视距(Non Line of Sight,NLOS)路径的传播链路。研究了这些链路的复杂信道冲激响应,考虑了多径效应的影响并据此推导出了完整的信道矩阵,分析了该信道模型在不同模型参数下的统计特性。基于这些理论推导,进一步研究了双IRS辅助空对地通信信道模型的传播特性。仿真结果表明,相较于单IRS配置,双IRS在提升系统性能方面具有显著优势,为进一步优化和设计基于IRS的空对地无线通信系统提供了有价值的参考。
文摘为了保证水下设备的长期稳定通信,提出了一种基于改进的快速边缘似然最大化的稀疏贝叶斯学习(sparse Bayesian learning based on improved fast marginal likelihood maximization, IFM-SBL)算法,对水声信道进行低复杂度、高性能的估计。特别是在低信噪比情况下,通过阈值去噪和离散傅里叶变换降噪,可以进一步提升算法的性能。仿真和海试结果表明,所提的IFM-SBL信道估计后的输出误码率与基于期望最大化的稀疏贝叶斯学习(sparse Bayesian learning based on expectation maximization, EM-SBL)算法相似,且验证了算法在低信噪比和快慢时变信道中都具有良好的鲁棒性。在运行速度方面,FM-SBL算法与IFM-SBL算法比EM-SBL算法提高了约90%,大大减少了信道估计时间。
