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Calculation method for bending-warping shear stress of single-box multicell box girders 认领 引用
1
作者 ZHANG Yuyuan MA Xiao +1 位作者 ZHANG Yuanhai FAN Jiang 《Journal of Southeast University(English Edition)》 EI CAS 2025年第4期493-500,共8页
To investigate the influence of the shear lag effect on the bending shear stress of single-box multicell box gird-ers(MCBG),the shear lag warping additional deflection is selected as the generalized displacement.The g... To investigate the influence of the shear lag effect on the bending shear stress of single-box multicell box gird-ers(MCBG),the shear lag warping additional deflection is selected as the generalized displacement.The governing dif-ferential equations and boundary conditions for the shear lag of the MCBG are derived using the energy variational method.Based on the shear lag warping deformation state of the MCBG and by employing the microelement equilib-rium differential equation and the coordination conditions for shear lag warping deformation,the calculation method for the bending-warping shear stress of the MCBG is de-rived,and the influence of the width-to-span and height-to span ratios on bending-warping shear stress is analyzed.Ex-ample analysis shows that the bending-warping shear stress of the MCBG calculated by the proposed calculation method coincides with the finite element solution,and the warping shear stress satisfies the self-balancing condition of shear warping,thus verifying the accuracy of the proposed method.The warping shear stress exhibits an antisymmetric distribution about the vertical axis of symmetry and has a weakening effect on the shear stress of the elementary beam(EB).The larger the width-to-span ratio is,the larger the proportion of the warping shear stress of the EB.The larger the height-to-span ratio is,the smaller the proportion of the warping shear stress and the more significant the influence of the width-to-span ratio.The more the number of cells is,the smaller the influence of the warping shear stress on the total bending shear stress.The influence of the shear lag ef-fect can be ignored in the calculation of the bending shear stress of three or more cells in the MCBG. 展开更多
关键词 single-box multicell box girders(MCBG) shear lag shear warping coordination conditions shear stress parametric analysis
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Grant-Free Random Access in Pilot-Reused Multicell Massive MIMO Systems with Backoff Mechanisms 认领 引用 被引量：2
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作者 Qi Zhang Jun Zhang Shi Jin 《China Communications》 SCIE CSCD 2023年第9期185-195,共11页
Grant-free random access(RA)is attractive for future network due to the minimized access delay.In this paper,we investigate the grantfree RA in multicell massive multiple-input multipleoutput(MIMO)systems with pilot r... Grant-free random access(RA)is attractive for future network due to the minimized access delay.In this paper,we investigate the grantfree RA in multicell massive multiple-input multipleoutput(MIMO)systems with pilot reuse.With backoff mechanism,user equipments(UEs)in each cell are randomly activated,and active UEs randomly select orthogonal pilots from a predefined pilot pool,which results in a random pilot contamination among cells.With the help of indicators that capture the uncertainties of UE activation and pilot selection,we derive a closed-form approximation of the spectral efficiency per cell after averaging over the channel fading as well as UEs’random behaviors.Based on the analysis,the optimal backoff parameter and pilot length that maximize the spectral efficiency can be obtained.We find that the backoff mechanism is necessary for the system with large number of UEs,as it can bring significant gains on the spectral efficiency.Moreover,as UE number grows,more backoff time is needed. 展开更多
关键词 backoff mechanism grant-free RA multicell massive MIMO
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A superposition scheme for downlink multicell processing with finite backhaul capacity 认领 引用
3
作者 Yi Xiao Wu Mingzhan Liu Nan 《Journal of Southeast University(English Edition)》 EI CAS 2017年第3期253-259,共7页
In the scenario of downlink multicell processing with finite backhaul capacity in the case of two base stations and two mobile users, by regarding the channel as a multiple access diamond channel with two destinations... In the scenario of downlink multicell processing with finite backhaul capacity in the case of two base stations and two mobile users, by regarding the channel as a multiple access diamond channel with two destinations, an achievability scheme that sends correlated codewords through the multiple access channel with common data is proposed. By considering the superposition structure, fully correlated codewords can be supported by the proposed scheme, which can benefit the system throughput in the case of a relatively-large-capacity backhaul. First, an achievable region for the achievable theory is given and it is proved from the perspective of information theory. Then, in the Gaussian scenario, a simulation combining dirty-paper coding and power allocating is provided for the achievable region. Simulation results demonstrate that when the backhaul capacity is relatively large, the proposed scheme outperforms the existing achievability scheme without the superposition structure. 展开更多
关键词 multicell processing finite backhaul capacity superposition dirty-paper coding power allocating
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爱立信GSM Multicell站系统简介 认领 引用
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作者 费国臻 《移动通信》 2001年第2期35-37,共3页
本文介绍爱立信 GSM Multicell站系统的原理和两种基本类型的基站结构，以及安装中容易出现的一些问题。
关键词 爱立信 GSM MultiCell 移动通信 基站系统
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Generalized Distributed Multicell Architecture:Group Cell 认领 引用
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作者 Tao Xiaofeng Wu Chunli Xu Xiaodong 《ZTE Communications》 2006年第2期7-10,共4页
In order to make full use of advanced technologies for future mobile communications systems such as Space Time Code(STC),Joint Transmission(JT)and Multiple Input Multiple Output(MIMO),and to meet the requirements of h... In order to make full use of advanced technologies for future mobile communications systems such as Space Time Code(STC),Joint Transmission(JT)and Multiple Input Multiple Output(MIMO),and to meet the requirements of high-bit-rate multimedia services,new network topologies should be studied.Generalized distributed multicell architecture can take full advantage of multi-antenna technologies and solve the problem of frequent handover caused by higher carrier frequencies.Group handover,the handover policy based on the architecture,can eliminate the cell edge effect.Furthermore,by applying the concept of group handover to 3G mobile communication systems,the Fast Cell Group Selection(FCGS)scheme can effectively improve the data rate for cell edge users. 展开更多
关键词 Figure cell IEEE Radio USA Generalized Distributed Multicell Architecture more GPP MT
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A New Mechanism of Convective Cell Regeneration and Development Within a Two-Dimensional Multicell Storm 认领 引用 被引量：2
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作者 鲍旭炜 谈哲敏 《Acta meteorologica Sinica》 2009年第4期413-427,共15页
In this study, based on simulations of a two-dimensional multicell storm under a ground-layer upshear （Uz〈0） by a mesoscale numerical model, a new mechanism of cell regeneration and development within the multicell... In this study, based on simulations of a two-dimensional multicell storm under a ground-layer upshear （Uz〈0） by a mesoscale numerical model, a new mechanism of cell regeneration and development within the multicell storm at the ＂less than optimal shear＂ state.is proposed. In the presence of a ground-layer upshear, the circulation associated with the surface cold pool is not counteracted by that associated with the ambient wind sl^ear, and the density current extends out faster, making the multicell storm stay at the ＂less than optimal shear＂ state. As a result, a new cell is triggered by the strong vertical perturbation ahead of the mature convection, rather than by the split-up from the updraft at the leading edge of the surface cold pool as well as the gust front. The latter is the mechanism at the ＂optimal＂ state proposed by Lin et al. in 1998. In the new mechanism, the regenerated cell grows fast with the incident warm moist air from the upstream of the multicell storm, and tends to cut off the moist airflow into the mature convection at its western sector. Consequently, the mature convection would weaken, be replaced, and eventually decay. Actually, these two different mechanisms come into play in a way depending on the relationship between the circulation of the low-level shear and that of the cold pool. When the circulation of the cold pool is stronger than that of the wind shear, the multicell storm is at the ＂less than optimal shear＂ state, and the new convective cell is produced by the disturbance ahead of the mature cell. When the circulation of the cold pool is weaker, the cell regeneration is dominated by the mechanism at the ＂optimal＂ state, and the new cell is split from the gust front updraft. Therefore, these two mechanisms are not contradictive. With a moderate ground-layer upshear, they can alternately operate within a multicell storm. 展开更多
关键词 multicell storm squall line low-level shear cold pool convective cell
New method for estimating flying capacitor voltages in stacked multicell and flying capacitor multicell converters 认领 引用
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作者 Arash KHOSHKBAR SADIGH Gevorg B.GHAREHPETIAN Seyed Hossein HOSSEINI 《Journal of Zhejiang University-Science C(Computers and Electronics)》 2010年第8期654-662,共9页
Multicell converters are an interesting alternative for medium voltage and high power applications,because of the increased number of output voltage levels and apparent frequency.The two most significant types of mult... Multicell converters are an interesting alternative for medium voltage and high power applications,because of the increased number of output voltage levels and apparent frequency.The two most significant types of multicell converter are the flying capacitor multicell (FCM) converter and its derivative,stacked multicell (SM) converter.Balancing flying capacitor voltages is an important constraint to the proper performance of FCM and SM converters.Thus,observation of the flying capacitor voltages used in active control is valuable,but using voltage sensors for observation increases cost and size of the converter.This paper deals with a new strategy to estimate the flying capacitor voltages of both FCM and SM converters.The proposed strategy is based on a discrete time model of the converter and uses only a load current sensor.The circuit was simulated using PSCAD/EMTDC software and simulation results were presented to validate the effectiveness of the proposed estimation strategy in observing the flying capacitor voltages.Simplicity is the most significant advantage of the proposed strategy,its performance being based on simple equations. 展开更多
关键词 Flying capacitor multicell converter Stacked multicell converter Flying capacitor voltage Phase shifted sinusoidal pulse width modulation
THE NEW SUPER-HIGH-SPEED DIGITAL CIRCUIT BASED ON LINEAR AND-OR GATES 认领 引用
8
作者 王守觉 石寅 +1 位作者 吴训威 金瓯 《Journal of Electronics(China)》 1995年第4期289-297,共9页
The paper reveals the relation between the linear AND-OR gate and the emitter function logic. With theoretic calculation and PSPICE simulation, the paper proves that the linear AND-OR gates can work at super-high-spee... The paper reveals the relation between the linear AND-OR gate and the emitter function logic. With theoretic calculation and PSPICE simulation, the paper proves that the linear AND-OR gates can work at super-high-speed and can be multi-cascaded. On the basis of analyzing the high-speed switch units which coordinate with linear AND-OR gates, two kinds of emitter coupled logic circuits are designed. The paper also discusses the design principles of super-high-speed digital circuits, and some examples of combinational and sequential circuits using linear AND-OR gate are given. 展开更多
关键词 linear AND-OR gate Super-high-speed digital circuits DYL(Duo Yuan Logic, it means multicell type logic circuits
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Numerical Analysis of the Transient Process of Flow and Heat Transfer at High Rayleigh Number in a Partially Open Habitat Heated from Above 认领 引用
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作者 Kodjo Kpode Yawovi Nougbléga +1 位作者 Cheikh Mbow Magolmèèna Banna 《Open Journal of Fluid Dynamics》 2019年第3期253-267,共15页
In this work, we studied the thermoconvective instabilities in a pentagonal cavity containing a Newtonian fluid. The cavity provided with a side opening is uniformly heated from above by a constant heat flux. The natu... In this work, we studied the thermoconvective instabilities in a pentagonal cavity containing a Newtonian fluid. The cavity provided with a side opening is uniformly heated from above by a constant heat flux. The natural ventilation phenomenon in the classic habitat of the hot climate is thus numerically analyzed with unsteady natural convection equations formulated with vorticity and stream-function variables. The finite volume predictions of two-dimensional laminar natural convection at high Rayleigh number are presented. Results show that the incoming fresh air and the hot air discharge begin with the late start of the convection. The phenomenon intensifies with time and the birth of instabilities improves the homogenisation of temperatures which imply the elimination of very cold and very hot areas. However, the competition between the incoming fresh air and the hot air expansion leads to a perpetual displacement of the thermal front. The cross-sections at the opening of the incoming fresh and outgoing hot air are time-varying and the penetration depth of the fresh air is highlighted by the large convective cells originated from the aperture. The non monotonic variation of the Nusselt number reflects not only the multicell nature of the flow but also expresses the heat lost by the active walls due to the fresh air. 展开更多
关键词 Unsteady Natural Convection Natural Ventilation Multicell Flow Nusselt Number
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Studies of an LL-type 500 MHz 5-cell superconducting cavity at SINAP 认领 引用 被引量：1
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作者 侯洪涛 马震宇 +11 位作者 毛冬青 封自强 罗琛 是晶 王岩 李正 徐凯 赵玉彬 郑湘 赵申杰 张志刚 刘建飞 《Chinese Physics C》 SCIE CAS CSCD 2015年第4期67-72,共6页
A low loss- （LL） type 500 MHz 5-cell superconducting niobium prototype cavity with a large beam aperture has been developed successfully including the optimization, the deep drawing and electron beam welding, the su... A low loss- （LL） type 500 MHz 5-cell superconducting niobium prototype cavity with a large beam aperture has been developed successfully including the optimization, the deep drawing and electron beam welding, the surface treatment and the vertical testing. The performance of the fundamental mode was optimized and the higher order modes were damped by adopting an enlarged beam pipe for propagation. Surface preparation or treatment including mechanical polishing, buffered chemical polishing and high pressure rinsing with ultra-pure water and so on was carried out carefully to ensure a perfect inner surface condition. The vertical testing results show that the accelerating voltage higher than 7.5 MV was obtained while the quality factor was better than 1× 109 at 4.2 K. No obvious multipacting or field emission was found during the test. However, a quench happened while increasing the field a little higher than 7.5 MV that at present limited the cavity performance. 展开更多
关键词 superconducting niobium cavity low loss multicell fabrication optimization vertical test
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