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非饱和黄土的水蒸气吸附特性

土木与环境工程学报（中英文） 2025年第1期47卷 80-88页

作者：符文媛刘德仁王旭李建东马玥兰州交通大学土木工程学院兰州730070 兰州交通大学道桥工程灾害防治技术国家地方联合工程实验室兰州730070

为研究非饱和黄土对水蒸气的吸附特性,采用蒸汽平衡法开展不同湿度环境下的等温吸附试验,分析水蒸气在非饱和黄土表面的吸附行为,并探讨温度、矿物成分及含量、干密度对土体吸附性能的影响。结果表明:非饱和黄土水蒸气吸附量随相对湿度... 详细信息

为研究非饱和黄土对水蒸气的吸附特性,采用蒸汽平衡法开展不同湿度环境下的等温吸附试验,分析水蒸气在非饱和黄土表面的吸附行为,并探讨温度、矿物成分及含量、干密度对土体吸附性能的影响。结果表明:非饱和黄土水蒸气吸附量随相对湿度的增加而增加,整个过程包含了单层吸附、多层吸附和毛细凝聚3个阶段,且GAB模型可以用来描述非饱和黄土的水蒸气吸附过程;水蒸气吸附量与温度之间存在明显的负相关关系,相对湿度恒定,水蒸气吸附量随温度的升高而降低;非饱和黄土的水蒸气吸附与矿物组成密切相关,黏土矿物含量直接影响其水蒸气吸附能力;此外,干密度对水蒸气吸附量的影响可分为两个阶段,在相对湿度RH<80%时,水蒸气吸附量随干密度的增大而增大,直到进入毛细凝聚阶段,随着干密度的增大,水蒸气吸附量不再增大反而有所降低。

关键词：非饱和黄土水蒸气吸附蒸汽平衡法等温吸附曲线吸附特性

Bayesian integer frequency offset estimator for MIMO-OFDM systems

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Journal of Systems Engineering and Electronics 2008年第6期19卷 1109-1114页

作者： Zhao linjing Lu Zhuo li jiandong Broadband Wireless Communications Lab Information Science Inst. State Key Lab of ISN Xidian Univ. Xi'an 710071 P. R. China

Carrier frequency offset （CFO） in MIMO-OFDM systems can be decoupled into two parts： fraction frequency offset （FFO） and integer frequency offset （IFO）. The problem of IFO estimation is addressed and a new IFO estimator based on the Bayesian philosophy is proposed. Also, it is shown that the Bayesian IFO estimator is optimal among all the IFO estimators. Furthermore, the Bayesian estimator can take advantage of oversampling so that better performance can be obtained. Finally, numerical results show the optimality of the Bayesian estimator and validate the theoretical analysis.

关键词： multiple-input-multiple-oputput orthogonal frequency-division multiplexing integer frequency offset estimation

Opportunistic Vector Perturbation with Superposition Signalling

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China Communications 2015年第12期12卷 160-165页

作者： CHEN Rui li Changle li jiandong State Key Laboratory of Integrated Service Networks Xidian University

In this letter,we first put forward a new basic problem to the famous vector perturbation(VP) precoding that whether the extended constellation of VP could transmit more information ***,we propose an opportunistic vector perturbation(OVP) precoding with superposition signalling scheme,which is aimed at getting the performance of VP closer to capacity *** main idea is using subsequent recoverable data symbol vector to perturb currently transmitting data symbol vector *** and simulation results show that the proposed OVP can transmit more valid information bits than conventional VP at the same transmit power,modulation order and number of antennas.

关键词： transmit symbol opportunistic constellation perturbation subsequent closer downlink aimed antenna

Interannual Relationship between Summer North Atlantic Oscillation and Subsequent November Precipitation Anomalies over Yunnan in Southwest China

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Journal of Meteorological Research 2022年第5期36卷 718-732页

作者： Shabin HAO jiandong li Jiangyu MAO State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 University of Chinese Academy of Sciences Beijing 100049

The summer North Atlantic Oscillation(SNAO)strongly affects the climate variability over Europe and downstream East Asia similar to its winter *** study thus investigates the interannual relationship between SNAO and the subsequent autumn precipitation anomalies over Yunnan,Southwest China and related physical mechanisms based on reanalysis data during 1958–*** results show that the interannual variations in SNAO exhibit a significant positive correlation with anomalies of Yunnan precipitation in *** analyses demonstrate that for the positive SNAO phase,the positive sea surface temperature anomalies(SSTAs)in midlatitude North Atlantic as part of a tripole SSTA tend to weaken from summer to November through changes in surface heat *** turn,the predominately negative SSTA in tropical North Atlantic that persists into November induces an anomalous cyclone at midlatitudes,which triggers two middle–upper tropospheric wave trains propagating from midlatitude North Atlantic to *** subtropical wave train propagates eastward along the subtropical westerly jet,and the mid–high latitude wave train follows the great circle path across Scandinavia and central Asia to the Tibetan *** wave trains favor development of an anomalous cyclone over the southern Tibetan *** upper-tropospheric divergent condition on the southeastern side of the anomalous cyclone is dynamically conducive to locally ascending motion over Yunnan,thus producing above-normal *** opposite situation occurs in the negative SNAO phase.A coupled model reproduces well the wave train propagation and thereby confirms the positive relationship between SNAO and Yunnan precipitation in November.

关键词： summer North Atlantic Oscillation(SNAO) Yunnan precipitation interannual variability Rossby wave propagation

Successive Interference Cancellation and Alignment in K-User MIMO Interference Channels with Partial Unidirectional Strong Interference

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China Communications 2022年第2期19卷 118-130页

作者： Long Suo Hongyan li Shun Zhang jiandong li State Key Laboratory of Integrated Service Networks Xidian UniversityXi’an 710071China Guangzhou Institute of Technology Xidian UniversityGuangzhou 510000China

Recently cellular networks have been densely and heterogeneously deployed indoors and outdoors to expand the network capacity,and thus the in-building propagation loss and the transmit power diversity of access points will exacerbate link heterogeneity and result in partial unidirectional strong *** make full use of the strong interference feature,we propose the successive interference cancellation and alignment(SICA)scheme in the K-user interference channel with partial unidirectional strong *** is designed to transmit two kinds of data streams simultaneously,the alignment streams and superposition *** alignment streams will follow the interference alignment criterion to maintain the optimal degrees of freedom(DoF)performance;the superposition streams are handled via successive interference cancellation at all the strongly interfered receivers to improve the overall achievable *** joint transceiver designs for SICA is modeled as a weighted sum rate(WSR)maximization problem,and then can be alternately solved for a local optimum according to the optimality equivalence between WSR and its corresponding weighted mean square error(WMMSE)*** results have confirmed the sum rate improvement and DoF optimality of the proposed SICA scheme.

关键词： interference alignment successive interference cancellation interference management ultra dense networks

The Effect of Internal Delamination Damage on the Tensile Strength of Aeronautical Composites

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Acta Mechanica Solida Sinica 2022年第6期35卷 979-986页

作者： Qiang Wang Qiuyu Chen Yujie Chen jiandong li Qun li School of Equipment Management and Unmanned Aerial Vehicle Engineering Air Force Engineering UniversityXi’an710051China State Key Laboratory for Strength and Vibration of Mechanical Structures School of AerospaceXi’an Jiaotong UniversityXi’an710049China School of Air and Missile Defence Air Force Engineering UniversityXi’an710051China

For aeronautical composite materials,the appearance of internal delamination has a fatal impact on their mechanical properties and may even seriously threaten aircraft flight *** this study,the effect of internal delamination damage with different sizes and depths on the tensile strength of aeronautical composites was ***,based on carbon-fiber-reinforced composites commonly used in aircraft,laminate specimens with internal delamination damages of different depths and diameters were fabricated,and tensile tests of composite materials were carried ***,the finite element model for the carbon-fiber-reinforced laminate specimens was established,and the validity of the model was verified by comparing its simulation results with the experimental ***,by changing the geometric parameters of the internal delamination damage model,the influence of delamination damage on the tensile strength of carbon-fiber-reinforced composites was analyzed and *** results show that,on the one hand,for the internal delamination damages of the same area,the closer is the delamination damage to the surface layer,the lower is the tensile *** particular,the closer is the delamination damage to the surface layer,the greater is the decrease in tensile strength,which exhibits an obvious nonlinear *** the other hand,for the internal delamination defects of the same depth,the difference in delamination area has little effect on the tensile *** law provides a reference for the damage detection and maintenance focus of aeronautical composite structures,which is of great significance to ensure the safe use of aeronautical composites.

关键词： Aeronautical composites Carbon fiber laminate Delamination damage Tensile strength Finite element simulation

Observational Characteristics of Cloud Radiative Effects over Three Arid Regions in the Northern Hemisphere

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Journal of Meteorological Research 2017年第4期31卷 654-664页

作者： jiandong li Tianhe WANG Ammara HABIB State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of Sciences Key Laboratory for Semi-Arid Climate Change of the Ministry of Education College of Atmospheric SciencesLanzhou University

Cloud–radiation processes play an important role in regional energy budgets and surface temperature changes over arid regions. Cloud radiative effects（CREs） are used to quantitatively measure the aforementioned climatic role. This study investigates the characteristics of CREs and their temporal variations over three arid regions in central Asia（CA）, East Asia（EA）, and North America（NA）, based on recent satellite datasets. Our results show that the annual mean shortwave（SW） and net CREs（SWCRE and NCRE） over the three arid regions are weaker than those in the same latitudinal zone of the Northern Hemisphere. In most cold months（November–March）, the longwave（LW）CRE is stronger than the SWCRE over the three arid regions, leading to a positive NCRE and radiative warming in the regional atmosphere–land surface system. The cold-season mean NCRE at the top of the atmosphere（TOA） averaged over EA is 4.1 W m^-2, with a positive NCRE from November to March, and the intensity and duration of the positive NCRE is larger than that over CA and NA. The CREs over the arid regions of EA exhibit remarkable annual cycles due to the influence of the monsoon in the south. The TOA LWCRE over arid regions is closely related to the high-cloud fraction, and the SWCRE relates well to the total cloud fraction. In addition, the relationship between the SWCRE and the low-cloud fraction is good over NA because of the considerable occurrence of low cloud. Further results show that the interannual variation of TOA CREs is small over the arid regions of CA and EA, but their surface LWCREs show certain decreasing trends that correspond well to their decreasing total cloud fraction. It is suggested that combined studies of more observational cloud properties and meteorological elements are needed for indepth understanding of cloud–radiation processes over arid regions of the Northern Hemisphere.

关键词： arid region cloud fraction cloud radiative effects

Adaptive joint bandwidth and power allocation in heterogeneous wireless access environment

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Science China(Information Sciences) 2014年第6期57卷 89-102页

作者： YAN JiLei li jiandong ZHAO linJing Broadband Wireless Communications Laboratory Information Science InstituteState Key Laboratory of ISNXidian University

Joint bandwidth and power allocation for a multi-radio access(MRA)system in a heterogeneous wireless access environment is *** both the number of users being served by the system and the wireless channel state are time-varying,the optimal resource allocation is no longer a static optimum and will change with the varying network ***,distributed resource allocation algorithms that require iterative updating and signaling interactions cannot converge in negligible ***,it is unrealistic to assume that the active user number and the wireless channel state remain unchanged during the *** this paper,we propose an adaptive joint bandwidth and power allocation algorithm based on a novel iteration stepsize selection method,which can adapt to the varying network state and accelerate the convergence rate.A distributed solution is also designed for the adaptive joint resource allocation *** results show that the proposed algorithm can not only track the varying optimal resource allocation result much more quickly than a traditional algorithm with fixed iteration stepsize,but can also reduce the data transmission time for users and increase the system throughput.

关键词： heterogeneous wireless networks multi-radio access system resource allocation network utility maximization adaptive stepsize

A Comparative Study on the Dominant Factors Responsible for the Weaker-than-expected El Ni?o Event in 2014

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Advances in Atmospheric Sciences 2015年第10期32卷 1381-1390页

作者： li Jianying liU Boqi li jiandong MAO Jiangyu State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences Chinese Academy of Meteorological Sciences Joint Center for Global Change Studies

Anomalous warming occurred in the equatorial central-eastern Pacific in early May 2014, attracting much attention to the possible occurrence of an extreme E1 Nifio event that year because of its similarity to the situation in early 1997. However, the subsequent variation in sea surface temperature anomalies （SSTAs） during summer 2014 in the tropical Pacific was evidently different to that in 1997, but somewhat similar to the situation of the 1990 aborted E1 Nifio event. Based on NCEP （National Centers for Environmental Prediction） oceanic and atmospheric reanalysis data, the physical processes responsible for the strength of E1 Nifio events are examined by comparing the dominant factors in 2014 in terms of the preceding instability of the coupled ocean-atmosphere system and westerly wind bursts （WWBs） with those in 1997 and 1990, separately. Although the unstable ocean-atmosphere system formed over the tropical Pacific in the preceding winter of 2014, the strength of the preceding instability was relatively weak. Weak oceanic eastward-propagating downwelling Kelvin waves were forced by the weak WWBs over the equatorial western Pacific in March 2014, as in February 1990. The consequent positive upper-oceanic heat content anomalies in the spring of 2014 induced only weak positive SSTAs in the central-eastern Pacific-unfavorable for the subsequent generation of summertime WWB sequences. Moreover, the equatorial western Pacific was not cooled, indicating the absence of positive Bjerknes feedback in early summer 2014. Therefore, the development of E1 Nifio was suspended in summer 2014.

关键词： El Nino event westerly wind burst instability of coupled ocean-atmosphere system positive Bjerknes feedback