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Science China(Information Sciences) 2013年第6期56卷 115-127页

作者： xu ding FENG ZhiYong ZHANG Ping Key Laboratory of Universal Wireless Communications Ministry of EducationBeijing University of Posts and Telecommunications

In this paper,we consider a spectrum sharing cognitive radio network coexisting with a primary ***,the channel state information(CSI) between the secondary transmitter and the primary receiver is assumed to be outdated due to channel feedback *** secondary user(SU) is assumed to satisfy a given delay quality-of-service(QoS) constraint as well as the average interference power *** aim to derive the maximum arrival rate of the SU under aforementioned constraints with the outdated *** this respect,we derive the optimal power allocation to achieve the maximum effective capacity,and further derive the effective *** closed-form expressions for the lower and upper bounds on the effective capacity are also *** addition,we obtain the effective capacities under two widely adopted adaptive transmission schemes,i.e.,optimal power and rate allocation(OPRA) and truncated channel inversion with fixed rate(TIFR).Numerical results are conducted to corroborate our *** is shown that the effective capacities of the SU under various transmission schemes are insensitive to the channel correlation coefficient especially under low channel correlation *** is also shown that the lower and upper bounds on the effective capacity are significantly tight under stringent delay QoS constraint.

关键词： cognitive radio effective capacity outdated channel feedback delay QoS constraint interferencepower constraint

Improved Upper Bound for Generalized Acyclic Chromatic Number of Graphs

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Acta Mathematicae Applicatae Sinica 2018年第4期34卷 798-800页

作者： Jian-sheng CAI xu-ding ZHU School of Mathematics and Information Sciences Weifang University Weifang 261061 China Department of Mathematics Zhejiang Normal University Jinhua 321004 China

A vertex coloring of a graph G is called r-acyclic if it is a proper vertex coloring such that every cycle D receives at least min{｜D｜, r} colors. The r-acyclic chromatic number of G is the least number of colors in an r-acyclic coloring of G. We prove that for any number r ≥ 4, the r-acyclic chromatic number of any graph G with maximum degree △ ≥ 7 and with girth at least（r-1）△ is at most（4r-3）△.

关键词： girth coloring acyclic coloring τ-acyclic coloring Lopsided local lemma

Downregulation of Col lal induces differentiation in mouse spermatogonia

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Asian Journal of Andrology 2012年第6期14卷 842-849页

作者： Sun-Hong Chen ding Li Chen xu Department of Histology and Embryology Shanghai Jiao Tong University School of Medicine Shanghai Key Laboratory of Reproductive Medicine Shanghai 200025 China

Col la I （one of the subunit of collagen type I） is a collagen, which belongs to a family of extracellular matrix （ECM） proteins that play an important role in cellular proliferation and differentiation. However, the role of Col lal in spermatogenesis, especially in the control of proliferation and differentiation of spermatogonial stem cells （SSCs）, remains unknown. In this study, we explored effects of downregulation of Collal on differentiation and proliferation of mouse spermatogonia. Loss-of-function study revealed that Oct4 and Plzf, markers of SSC self-renewal, were significantly decreased, whereas the expression of c-kit and haprin, hallmarks of SSC differentiation, was enhanced after Col la I knockdown. Cell cycle analyses indicated that two-thirds of spermatogonia were arrested in S phase after Collal knockdown. In vivo experiments, DNA injection and electroporation of the testes showed that spermatogonia self-renewal ability was impaired remarkably with the loss-of-function of Collal. Our data suggest that silencing of Collal can suppress spermatogonia self-renewal and promote spermatogonia differentiation.

关键词： Collal differentiation extracellular matrix (ECM) spermatogenesis spermatogonia

Topochemical polymerization of hydrogen-bonded organic framework for supporting ultrafine palladium nanoparticles

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Science China Chemistry 2023年第7期66卷 2019-2027页

作者： xu ding Bin Han Baoqiu Yu Hailong Wang Jianzhuang Jiang Beijing Advanced Innovation Center for Materials Genome Engineering Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline MaterialsDepartment of Chemistry and Chemical EngineeringSchool of Chemistry and Biological EngineeringUniversity of Science and Technology BeijingBeijing 100083China

Topochemical polymerization of molecular crystals into porous materials is of significance due to their promising applications in the field of adsorption and catalysis,yet rarely reported due to the synthesis ***,a hydrogen-bonded organic framework(HOF-45)has been fabricated by the crystallization of a cage-like building block containing three alkynyl *** exhibits almost mesoporous structure demonstrated by single crystal X-ray diffraction ***-driven topochemical polymerization of HOF-45 with ethanedithiol covalently links alkynyl groups in HOF-45,generating a hydrogen-bond and covalentbond cross-linked material(HOF-45C).In contrast to HOF-45,cross-linked HOF-45C retains the crystalline nature and displays improved solution resistence according to the powder X-ray diffraction *** particular,HOF-45C is able to support the growth of ultrafine palladium nanoparticles with the average size of ca.1.9 nm for rapidly promoting the degradation of nitrophenol,methyl orange,and congo red with the help of NaBH_(4)as well as Suzuki-Miyaura coupling *** work inputs a new idea on the HOFs application in preparing covalent-linked porous organic materials.

关键词： hydrogen-bonded organic frameworks topochemical polymerization palladium nanoparticles nitrophenol degradation organic dyes degradation Suzuki-Miyaura coupling reaction

Influences of labor migration on rural household land transfer:A case study of Sichuan Province,China

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Journal of Mountain Science 2018年第9期15卷 2055-2067页

作者： xu ding-de CAO Sha WANG xu-xi LIU Shao-quan Sichuan Center for Rural Development Research College of ManagementSichuan Agricultural UniversityChengdu 611130China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China College of Land and Resource China West Normal UniversityNanchong 637000China

The influence of labor migration on rural household land transfer has been hotly debated in academic circles, which focuses on whether part-time employment leads to land transfer. Using survey data on rural households in the Sichuan Province, and applying the theoretical framework of new economics of labor migration, this study explores the influences of labor migration on the direction and scale of land transfer from the perspective of rural household structure. The results indicate that: 1) the quantity of laborers has significant influence on the direction and scale of land transfer. The larger the on-farm labor variable(Labor), the lesser the possibility that land will be rented-out and the amount of land rented out will also be smaller. In addition, there is a greater probability that land will be rented-in and the amount of land rented-in will be greater. 2) The greater the ratio of off-farm laborers to rural household laborers(Off-farm) the greater the possibility that land will be rented-out. In addition the higher the ratio of on-farm laborers to the total household laborers(On-farm), the larger the possibility that land will be rented-in. Meanwhile, if the household has individuals at the age of 64 or older(Old) who are engaged in agriculture, there is a smaller possibility that land will be rentedout. 3) the ratio of part-time laborers to rural household laborers(Pluriactivity) have significant inverse U-shaped influences on the rent-in of land as well as the amount of land rented-in. The inflection points are 33.27% and 14.10%, respectively. Such findings confirm the significance of this study in better understanding the influence of labor migration on rural household land transfer.

关键词： Labor migration Part-time employment Land transfer direction Land transfer scale Ruralarea Sichuan Province

Throughput-oriented associated transaction assignment in sharding blockchains for IoT social data storage

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Digital Communications and Networks 2022年第6期8卷 885-899页

作者： Liping Tao Yang Lu xu ding Yuqi Fan Jung Yoon Kim School of Computer Science and Information Engineering Hefei University of TechnologyHefei230009China Engineering Research Center of Safety Critical Industrial Measurement and Control Technology Ministry of EducationHefei University of TechnologyHefei230009China Institute of Industry&Equipment Technology Hefei University of TechnologyHefei230009China Key Laboratory of Knowledge Engineering with Big Data(Hefei University of Technology) Ministry of EducationHefei230009China Graduate School of Game Gachon UniversitySeongnam-Si461-701South Korea

Blockchain is a viable solution to provide data integrity for the enormous volume of 5G IoT social data, while we need to break through the throughput bottleneck of blockchain. Sharding is a promising technology to solve the problem of low throughput in blockchains. However, cross-shard communication hinders the effective improvement of blockchain throughput. Therefore, it is critical to reasonably allocate transactions to different shards to improve blockchain throughput. Existing research on blockchain sharding mainly focuses on shards formation, configuration, and consensus, while ignoring the negative impact of cross-shard communication on blockchain throughput. Aiming to maximize the throughput of transaction processing, we study how to allocate blockchain transactions to shards in this paper. We propose an Associated Transaction assignment algorithm based on Closest Fit (ATCF). ATCF classifies associated transactions into transaction groups which are then assigned to different shards in the non-ascending order of transaction group sizes periodically. Within each epoch, ATCF tries to select a shard that can handle all the transactions for each transaction group. If there are multiple such shards, ATCF selects the shard with the remaining processing capacity closest to the number of transactions in the transaction group. When no such shard exists, ATCF chooses the shard with the largest remaining processing capacity for the transaction group. The transaction groups that cannot be completely processed within the current epoch will be allocated in the subsequent epochs. We prove that ATCF is a 2-approximation algorithm for the associated transaction assignment problem. Simulation results show that ATCF can effectively improve the blockchain throughput and reduce the number of cross-shard transactions.

关键词： IoT social data Blockchain Shar ding Associated transactions Transaction assi gnment

基于刚度折减法的岸边集装箱起重机结构损伤模拟

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起重运输机械 2025年第1期 38-44页

作者：秦仙蓉王令帅丁旭杨穹同济大学机械与能源工程学院上海201804

岸边集装箱桥式起重机是码头集装箱进行装卸的专业设备,其前大梁、梯形架和拉杆往往受到交变载荷、冲击载荷,且在露天码头环境下受到锈蚀、涂膜剥离、裂纹等故障的侵袭,这会对其结构的刚度产生较大影响。鉴于此,文中以岸边集装箱起重机... 详细信息

岸边集装箱桥式起重机是码头集装箱进行装卸的专业设备,其前大梁、梯形架和拉杆往往受到交变载荷、冲击载荷,且在露天码头环境下受到锈蚀、涂膜剥离、裂纹等故障的侵袭,这会对其结构的刚度产生较大影响。鉴于此,文中以岸边集装箱起重机为研究对象,提出了一种基于刚度折减法的岸边集装箱起重机损伤模拟方法 ,建立有限元模型对岸边集装箱起重机的前大梁、梯形架和拉杆分别进行损伤模拟,得到不同刚度折减程度下损伤状态的位移、应变等响应;同时,考虑到这3种损伤并不独立发生,采用正交试验方法基于该损伤模型对这3种损伤进行分组模拟,得到多损伤条件下的响应数据,从而进一步反映岸边集装箱起重机实际工况下的损伤规律。

关键词：岸边集装箱起重机刚度折减损伤模拟正交试验结构分析

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The Numerical Study of the S = 1/2 XXZ Chain

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Communications in Theoretical Physics 2001年第10期36卷 483-486页

作者： YE Fei ding Guo-Hui xu Bo-Wei Department of Physics Shanghai Jiao Tong University Shanghai 200030 China Department of Physics Shanghai Jiao Tong University Shanghai 200030 China Department of Physics Shanghai Jiao Tong University Shanghai 200030 China

We adopt the Lanczos method combined with the quantum conformal field theory to investigate the S = 1/2XXZ chain in detail. The bulk-limit ground state energy, the anomalous scaling dimension of the spin operators, theFermi velocity and the zero-temperature susceptibility are numerically calculated. The results agree to the exact solution well.

关键词： quantized spin models, strongly correlated electron systems, Lanczos method

Does labor off-farm employment inevitably lead to land rent out?Evidence from China

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Journal of Mountain Science 2019年第3期16卷 689-700页

作者： DENG Xin xu ding-de ZENG Miao QI Yan-bin College of Economics Sichuan Agricultural University Sichuan Center for Rural Development Research College of ManagementSichuan Agricultural University School of Economics Sichuan University

The focus of land economics is on how to decrease the misallocation of resources to achieve an optimal allocation of resources. Both the theories of new economics of labor migration(NELM) and the conclusions of empirical studies reveal that land resources will inevitably be reallocated(e.g., rented out) if the resources of family labor are reallocated(e.g., off-farm employment). However, this study reveals that off-farm employment does not inevitably lead to land rent out. More precisely, this study uses survey data on 8031 peasant households from 27 provinces in China and explores the relationship between off-farm employment and land rent out by describing spatial features and through empirical analysis(e.g., IV-Probit model and IV-Tobit model). The results show the following: 1) There is an indirect relationship between off-farm employment and land rent out regarding spatial area aggregation, i.e., regions with a higher ratio of off-farm employment also have a lower area of land rent out. 2) Off-farm employment is significantly positively correlated with the behavior of land rent out, but its square is significantly negatively correlated with the behavior, i.e., there is an inverted U-shaped relationship between off-farm employment and the behavior of land rent out, with the turning point being 55.55% offfarm employment. 3) Off-farm employment is significantly positively correlated with the area of land rent out, but its square is significantly negatively correlated with the area, i.e., there is an inverted Ushaped relationship between off-farm employment and the area of land rent out, with the turning point being 56.22% off-farm employment. This study helps explain why China has a high ratio of off-farm employment but a lower rate of land rent out.

关键词： Rural labor Off-farm employment Land rent out Rent out area China

Effects of heat treatment on properties of multi-element low alloy wear-resistant steel

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China Foundry 2007年第1期4卷 18-21页

作者： SONG xu-ding FU Han-guang School of Mechanical Engineering Chang ＇an University Xi ＇an 710064 China School of Material Engineering Xi＇an jiaotong University Xi＇an 710000 China

The paper has studied the mechanical properties and heat treatment effects on multi-element low alloy wear-resistant steel (MLAWS) used as a material for the liner of rolling mill torii. The results show that when quenched at 900-920℃ and tempered at 350-370℃, the MLAWS has achieved hardness above 60 HRC, tensile strength greater than 1 600 MPa, impact toughness higher than 18J/cm2 and fracture toughness greater than 37 MPa·m1/2. When the quenching temperature is lower than 900℃, the hardness of the MLAWS increases with the temperature. When the quenching temperature is higher than 900℃, the hardness decreases with the increase of temperature. At a quenching temperature below 920℃, the effect of quenching temperature on the impact toughness is not obvious. In quenching at above 920℃, impact toughness decreases as the temperature increases. When the tempering temperature is exceeding 450℃, the hardness begins to decrease significantly. Tempering at 350℃ has produced the best wear resistance on the MLAWS.

关键词： rolling mill torii liner heat treatment mechanical properties wear resistance