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Effective Capacity of URLLC over Parallel Fading Channels with Imperfect Channel State Information
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作者 Peng Hongsen Tao Meixia 《China Communications》 SCIE CSCD 2024年第5期45-63,共19页
This paper investigates the effective capacity of a point-to-point ultra-reliable low latency communication(URLLC)transmission over multiple parallel sub-channels at finite blocklength(FBL)with imperfect channel state... This paper investigates the effective capacity of a point-to-point ultra-reliable low latency communication(URLLC)transmission over multiple parallel sub-channels at finite blocklength(FBL)with imperfect channel state information(CSI).Based on reasonable assumptions and approximations,we derive the effective capacity as a function of the pilot length,decoding error probability,transmit power and the sub-channel number.Then we reveal significant impact of the above parameters on the effective capacity.A closed-form lower bound of the effective capacity is derived and an alternating optimization based algorithm is proposed to find the optimal pilot length and decoding error probability.Simulation results validate our theoretical analysis and show that the closedform lower bound is very tight.In addition,through the simulations of the optimized effective capacity,insights for pilot length and decoding error probability optimization are provided to evaluate the optimal parameters in realistic systems. 展开更多
关键词 effective capacity finite blocklength regime imperfect CSI parallel fading channels URLLC
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Experiment investigation on visualization and operating characteristics of closed loop plate oscillating heat pipe with parallel channels 被引量:1
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作者 SHI Wei-xiu PAN Li-sheng 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第9期2410-2418,共9页
Using ethanol or acetone as the working fluid, visualization of oscillations in steady state was observed visually by high-speed cameras, and temperature oscillating and heat transfer characteristics of closed-loop pl... Using ethanol or acetone as the working fluid, visualization of oscillations in steady state was observed visually by high-speed cameras, and temperature oscillating and heat transfer characteristics of closed-loop plate oscillating heat pipe with parallel channels(POHP-PC) were experimentally investigated by varying liquid filled ratios(50%, 70%, 85%), section scales(1 mm×1 mm and 1 mm×1.5 mm), inclination angles, working fluids and heating inputs. It was found that during operating there was mixed flow consisting of plug flow and annular flow in channels of oscillating heat pipe at steady-state. There was an equilibrium position for working fluid of condenser during oscillating, and periodic oscillations occurred up and down in the vicinity of equilibrium position. With heat input increasing, equilibrium position rose slowly as a result of vapor pressure of evaporation.Evaporation temperature oscillating amplitude possessed a trend of small-large-small and frequency trend was of small-large during steady-state. It may be generally concluded that temperature, whether evaporator or condenser, fluctuated sharply or rose continuously when oscillating heat pipe coming to dry burning state. Simultaneously, it was found that temperature difference of cooling water possibly dropped with heat input rising during dry burning state. Thermal resistance of No. 2 with acetone was lower than that of No. 1 during experiments, but No. 2 achieving heat transfer limit was earlier than No. 1. However, with ethanol, thermal resistance of No. 1 and No. 2 were similar with the heating input less than 110-120 W and filling ratios of 50% and 70%. And with filling ratio of 85%, heating transfer performance of No. 2 was better compared to No. 1 during all the experiments. 展开更多
关键词 closed loop with parallel channels plate oscillating heat pipe VISUALIZATION temperature oscillating heat transfer performance filling ratio section scale
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Lubrication performance of rapeseed oil-based nano-lubricants in parallel tubular channel angular pressing process 被引量:1
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作者 Mehdi KASAEIAN-NAEINI Ramin HASHEMI Ali HOSSEINI 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第5期1042-1049,共8页
Due to the biological risks of using the conventional lubricants,the vegetable oils have been considered nowadays.Besides,to improve the tribological properties of the vegetable oils in various applications like metal... Due to the biological risks of using the conventional lubricants,the vegetable oils have been considered nowadays.Besides,to improve the tribological properties of the vegetable oils in various applications like metal forming processes,nanoparticles have been used as additives.This research evaluated the lubrication performance of the Al2O3 and TiO2 nanoparticles dispersed in rapeseed oil during the parallel tubular channel angular pressing (PTCAP) process.The experimental PTCAP tests have been fulfilled under three lubrication conditions and the comparison between the PTCAP processed tubes has been performed in terms of the maximum forming force,surface roughness,and microhardness.The experimental results indicate that adding the mentioned nanoparticles has caused at least a 50% reduction in the maximum deformation load.Moreover,a remarkable decrement in the surface roughness of the formed tubes has been obtained. 展开更多
关键词 parallel tubular channel angular pressing nano lubricant nano-particle additives vegetable oil aluminum alloy
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A CODE DESIGN CRITERIA FOR NOT FULLY CONNECTED CHANNEL
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作者 Xiao Haiyong Bi Guangguo Zhang Peng Jin Xiufeng 《Journal of Electronics(China)》 2006年第2期193-196,共4页
There are parallel channels which are not fully connected in practice, such as Frequency Division Multiplex (FDM or Orthogonal FDM) systems. Conventional space-time codes can be used for such parallel channels but not... There are parallel channels which are not fully connected in practice, such as Frequency Division Multiplex (FDM or Orthogonal FDM) systems. Conventional space-time codes can be used for such parallel channels but not the optimal. Based on the derivation of PEP expression for codes transmitted on parallel block fading channels, criteria of codes design for not fully connected channels are proposed and are compared with Tarokh's criteria for fully connected channel. New codes for such channels are provided by systematical and exhaustive search. Simulation results show that these codes offer better performance on parallel FDM channels than other known codes. 展开更多
关键词 Block fading channel Parallel channel Space-time codes Orthogonal Frequency Division Multiplex (OFDM) DIVERSITY
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Mechanical force and cytoplasmic Ca^(2+) activate mechanosensitive BK channel in parallel
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作者 Hu-cheng Zhao,Fa Wang(Institute of Biomechanics and Medical Engineering,Department of Engineering Mechanics,Tsinghua University,Beijing 100084,China) 《医用生物力学》 EI CAS CSCD 2009年第S1期23-24,共2页
BK channels are widely expressed in both excitable and non-excitable cells and known to be involved in many physiological processes,such as vascular smooth tone regulation,neuronal firing and endocrine cell secretion[... BK channels are widely expressed in both excitable and non-excitable cells and known to be involved in many physiological processes,such as vascular smooth tone regulation,neuronal firing and endocrine cell secretion[1].Recently, the BK channels have 展开更多
关键词 BK activate mechanosensitive BK channel in parallel Mechanical force and cytoplasmic Ca
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Analytical and Computational Analysis of Flow Splitting in Multiple, Parallel Channels Systems
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作者 Alejandro I. Lazarte J. C. Ferreri 《World Journal of Nuclear Science and Technology》 2016年第3期170-190,共22页
Previous analytical results on flow splitting are generalized to consider multiple boiling channels systems. The analysis is consistent with the approximations usually adopted in the use of systems codes (like RELAP5 ... Previous analytical results on flow splitting are generalized to consider multiple boiling channels systems. The analysis is consistent with the approximations usually adopted in the use of systems codes (like RELAP5 and TRACE5, among others) commonly applied to perform safety analyses of nuclear power plants. The problem is related to multiple, identical, parallel boiling channels, connected through common plena. A theoretical model limited in scope explains this flow splitting without reversal. The unified analysis performed and the confirmatory computational results found are summarized in this paper. New maps showing the zones where this behavior is predicted are also shown considering again twin pipes. Multiple pipe systems have been found not easily amenable for analytical analysis when dealing with more than four parallel pipes. However, the particular splitting found (flow along N pipes dividing in one standalone pipe flow plus N -1 identical pipe flows) has been verified up to fourteen pipes, involving calculations in systems with even and odd number of pipes using the RELAP5 systems thermal-hydraulics code. 展开更多
关键词 Multiple Parallel Boiling channels Systems Asymmetric Splitting Flow Verification of Codes Systems Thermal-Hydraulics Codes Nuclear Engineering
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Numerical Simulation of Asymmetric Merging Flow in a Rectangular Channel
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作者 Abuzar Abid Siddiqui 《World Journal of Mechanics》 2016年第4期118-130,共13页
The steady, asymmetric and two-dimensional flow of viscous, incompressible and Newtonian fluid through a rectangular channel with splitter plate parallel to walls is investigated numerically. Earlier, the position of ... The steady, asymmetric and two-dimensional flow of viscous, incompressible and Newtonian fluid through a rectangular channel with splitter plate parallel to walls is investigated numerically. Earlier, the position of the splitter plate was taken as a centreline of channel but here it is considered its different positions which cause the asymmetric behaviour of the flow field. The geometric parameter that controls the position of splitter is defined as splitter position parameter a. The plane Poiseuille flow is considered far from upstream and downstream of the splitter. This flow-problem is solved numerically by a numerical scheme comprising a fourth order method, followed by a special finite-method. This numerical scheme transforms the governing equations to system of finite-difference equations, which are solved by point S.O.R. iterative method. In addition, the results obtained are further refined and upgraded by Richardson Extrapolation method. The calculations are carried out for the ranges -1 α R < 10<sup>5</sup>. The results are compared with existing literature regarding the symmetric case (when a = 0) for velocity, vorticity and skin friction distributions. The comparison is very favourable. Moreover, the notable thing is that the decay of vorticity to its downstream value takes place over an increasingly longer scale of x as R increases for symmetric case but it is not so for asymmetric one. 展开更多
关键词 Parallel Walls Rectangular channel with Parallel Splitter Special Finite-Difference Method S. O. R. and Richardson Extrapolation Methods
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Experimental study on flow excursion instability of supercritical hydrocarbon fuel in scramjet regenerative cooling parallel channels 被引量:2
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作者 Xiaoyong LIU Zhuqiang YANG +3 位作者 Ruipu MIAO Feng LIU Shujun ZHAO Qincheng BI 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2023年第1期201-215,共15页
Flow instability of supercritical hydrocarbon fuel is a crucial issue in scramjet regenerative cooling structure. In this study, flow excursion instability and flow distribution in parallel tubes were experimentally s... Flow instability of supercritical hydrocarbon fuel is a crucial issue in scramjet regenerative cooling structure. In this study, flow excursion instability and flow distribution in parallel tubes were experimentally studied for supercritical fluids. Two types of flow excursion occur in a single tube. Type Ⅰ and Type Ⅱ excursions, and they are corresponding to decreasing and increasing flow rate respectively. They can trigger flow maldistribution between parallel tubes and the hysteresis phenomenon of flow distribution. The effects of system parameters, including inlet temperature,system pressure, and heat flux, on flow distribution were analyzed. In addition, the relationship between flow excursion and the pseudo-critical interval proposed in the literature was established according to the heated tube outlet temperature at the onset of flow instability. Finally, the flow excursion instability boundary was obtained using two dimensionless parameters. These experimental results can provide helpful insight on the mechanism of Scramjet regenerative cooling. 展开更多
关键词 Flow distribution Ledinegg instability Onset of flow excursion Parallel channels Regenerative cooling SCRAMJET Supercritical flow
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Experimental Investigation on Flow Pattern and Bubble Behavior during Subcooled Flow Boiling of R1233zd(E)in Parallel Channels
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作者 FANG Yidong ZHANG Zhao +3 位作者 XU Dan WANG Yuchen YANG Huinan HUANG Yuqi 《Journal of Thermal Science》 SCIE EI CAS CSCD 2023年第6期2374-2385,共12页
In this study,the flow pattern and bubble behavior of R1233zd(E)during subcooled flow boiling in parallel channels are experimentally investigated with visualization and thermal measurement.The test section is compose... In this study,the flow pattern and bubble behavior of R1233zd(E)during subcooled flow boiling in parallel channels are experimentally investigated with visualization and thermal measurement.The test section is composed of 21 rectangular mini channels with the hydraulic diameter of 1.5 mm and the length of 140 mm.Bubbly flow,slug flow,churn flow and wavy-annular flow occur in sequence with the increase of vapor quality,while transient flow pattern transition process involving multiple flow patterns are also captured.The distribution of flow pattern is non-synchronized and axial-asymmetric,with earlier flow pattern transitions observed in peripheral channels away from the center axis.The initial nucleate site in each channel also show a random and axial-asymmetric distribution,while faster bubble growth can be noted in some channel under the comprehensive effects of liquid evaporation and bubble coalescence.The variation of heat transfer coefficient is correspondence to the flow pattern transition,showing different trends along the flow direction.The increase of mass flux can lead to delayed flow pattern transition and variation of heat transfer coefficient.In addition,higher heat transfer coefficient can be noted in channels away from the center axis. 展开更多
关键词 flow boiling flow pattern bubble behavior parallel channel VISUALIZATION
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Performance Assessment and Improvement of Photovoltaic-Thermal System based on Energy, Exergy, Economic and Environment Analysis
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作者 ZHOU Yuan WANG Jiangjiang +1 位作者 QIN Yanbo LIU Boxiang 《Journal of Thermal Science》 SCIE EI CAS CSCD 2024年第6期2166-2178,共13页
A photovoltaic thermal(PV/T)system with parallel cooling channels was designed in this work to decrease the PV panel temperature and improve its photoelectric conversion efficiency.A 4E analysis method(includes energy... A photovoltaic thermal(PV/T)system with parallel cooling channels was designed in this work to decrease the PV panel temperature and improve its photoelectric conversion efficiency.A 4E analysis method(includes energy,exergy,economic,and environmental aspects)was formulated to comprehensively evaluate the performances of the PV/T system,combining experimental and simulation studies.Firstly,the experiment was performed using water as the cooling medium.Results show that the PV/T system can reduce daily CO_(2) emissions by 1682.47-1705.98 g,and compared to the PV system,the added cooling module can increase electrical efficiency and environmental performance by 12.19%and 6.2%,respectively.When the mass flow of water rose from 0.017 kg/s to 0.023 kg/s,the electrical,thermal,and overall efficiencies were improved by 3.82%,11.36%,and 8.27%,respectively.Secondly,a numerical simulation model was constructed based on the experimental results to predict operations of the presented PV/T system using nanofluids as the cooling medium,including Ag,Al_(2)O_(3),and SiO_(2).Simulation results show that the Al_(2)O_(3)-nanofluid-based PV/T system has a higher application value,enabling an electrical efficiency of up to 15.13%.Its thermal efficiency can be enhanced by 5.43%when the volume fraction of Al_(2)O_(3);increases from 1%to 5%. 展开更多
关键词 photovoltaic/thermal system parallel cooling channels 4E analysis method NANOFLUID numer analysis
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Secure Transmission Scheme for Parallel Relay Channels Based on Polar Coding 被引量:3
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作者 Ce Sun Zesong Fei +2 位作者 Dai Jia Congzhe Cao Xinyi Wang 《Tsinghua Science and Technology》 SCIE EI CAS CSCD 2018年第3期357-365,共9页
This paper considers the use of polar codes to enable secure transmission over parallel relay channels.By exploiting the properties of polar codes over parallel channels, a polar encoding algorithm is designed based o... This paper considers the use of polar codes to enable secure transmission over parallel relay channels.By exploiting the properties of polar codes over parallel channels, a polar encoding algorithm is designed based on Channel State Information(CSI) between the legitimate transmitter(Alice) and the legitimate receiver(Bob).Different from existing secure transmission schemes, the proposed scheme does not require CSI between Alice and the eavesdropper(Eve). The proposed scheme is proven to be reliable and shown to be capable of transmitting information securely under Amplify-and-Forward(AF) relay protocol, thereby providing security against passive and active attackers. 展开更多
关键词 polar codes parallel channel relay channel secure transmission
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A NON LINEAR ANALYSIS OF TWO PHASE FLOW INSTA BILITY IN PARALLEL CHANNELS OF A BOILING SYSTEM
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作者 Zhou Yun long, Cheng Zhuo ming, Cai Hui Northeast China Institute of Electric Power Engineering, Jilin 132012, P.R.China (Received Sep. 18, 1998) 《Journal of Hydrodynamics》 SCIE EI CSCD 1999年第3期36-43,共8页
This paper proposes a non linear mathematical model of two phase flow instability in parallel channels of a boiling system. Close agreement is obtained between calculations based on this model and measurements of th... This paper proposes a non linear mathematical model of two phase flow instability in parallel channels of a boiling system. Close agreement is obtained between calculations based on this model and measurements of the stable boundary in a system of two channels. The model is also applied to the cases of three and four parallel channels. 展开更多
关键词 parallel channel flow instability mathematical model
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COMPETITIVE PARALLEL DISTRIBUTION CHANNELS WITH MOVE SEQUENCE
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作者 Yu QIAN 《Journal of Systems Science and Systems Engineering》 SCIE EI CSCD 2006年第1期114-123,共10页
关键词 parallel distribution channel Stackelberg game move sequence second-mover advantage
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Pragmatic Physical Layer Abstraction Method Based on Bit-LLR-Wise Exponential Effective SNR Mapping for Bit Interleaved Coded Orthogonal Frequency Division Multiplexing System 被引量:1
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作者 李孟实 俞晖 +1 位作者 罗汉文 徐友云 《Journal of Shanghai Jiaotong university(Science)》 EI 2014年第2期173-180,共8页
In this paper, we analyze the physical layer abstraction for bit interleaved coded orthogonal frequency division multiplexing(BIC-OFDM) system from a parallel bit channel perspective. By combining the exponential effe... In this paper, we analyze the physical layer abstraction for bit interleaved coded orthogonal frequency division multiplexing(BIC-OFDM) system from a parallel bit channel perspective. By combining the exponential effective SNR(signal-to-noise ratio) mapping(EESM) with the maximum a posteriori(MAP) algorithm, a bit LLR(log-likelihood ratio) wise EESM(BL-EESM) method is proposed. This method can abstract the link performance with high accuracy, especially for the case when channel estimation is imperfect. Afterward, the BL-EESM method is simplified by utilizing the non-linear quantization idea, which can reduce the times of exponential operation by two orders of magnitude at wide system bandwidth, yet shows little loss in accuracy. Our proposal can be applied to both system level simulations to save the time consumption and to practical terminals to facilitate the adaptive modulation and coding(AMC) procedure, bringing about throughput improvement at low hardware cost. 展开更多
关键词 physical layer abstraction parallel bit channel signal-to-noise ratio (SNR) exponential effective SNR mapping (EESM) adaptive modulation and coding (AMC) quantization
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Examples of Boundary Layers Associated with the Incompressible Navier-Stokes Equations
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作者 Xiaoming WANG 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2010年第5期781-792,共12页
The author surveys a few examples of boundary layers for which the Prandtl boundary layer theory can be rigorously validated.All of them are associated with the incompressible Navier-Stokes equations for Newtonian flu... The author surveys a few examples of boundary layers for which the Prandtl boundary layer theory can be rigorously validated.All of them are associated with the incompressible Navier-Stokes equations for Newtonian fluids equipped with various Dirichlet boundary conditions(specified velocity).These examples include a family of(nonlinear 3D) plane parallel flows,a family of(nonlinear) parallel pipe flows,as well as flows with uniform injection and suction at the boundary.We also identify a key ingredient in establishing the validity of the Prandtl type theory,i.e.,a spectral constraint on the approximate solution to the Navier-Stokes system constructed by combining the inviscid solution and the solution to the Prandtl type system.This is an additional difficulty besides the wellknown issue related to the well-posedness of the Prandtl type system.It seems that the main obstruction to the verification of the spectral constraint condition is the possible separation of boundary layers.A common theme of these examples is the inhibition of separation of boundary layers either via suppressing the velocity normal to the boundary or by injection and suction at the boundary so that the spectral constraint can be verified.A meta theorem is then presented which covers all the cases considered here. 展开更多
关键词 Boundary layer Navier-Stokes system Prandtl theory CORRECTOR Inviscid limit Spectral constraint Nonlinear plane parallel channel flow Nonlinear pipe flow Injection and suction
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