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Price-based time and energy allocation in cognitive radio multiple access networks with energy harvesting

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Science China(Information Sciences) 2017年第10期60卷 258-260页

作者： ding xu Qun LI Wireless Communication Key Lab of Jiangsu Province Nanjing University of Posts and Telecommunications

Cognitive radio(CR),a concept that can solve the conflict between spectrum scarcity and low spectrum utilization,has been researched widely recently[1].There are mainly three CR models:interweave,overlay and underlay[... 详细信息

关键词： CBS Price-based time and energy allocation in cognitive radio multiple access networks with energy harvesting

Effective capacity region and power allocation for two-way spectrum sharing cognitive radio networks

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Science China(Information Sciences) 2015年第6期58卷 126-135页

作者： xu ding LI Qun Wireless Communication Key Lab of Jiangsu Province Nanjing University of Posts and Telecommunications School of Computer Science and Technology Nanjing University of Posts and Telecommunications

In this paper, we consider a spectrum sharing cognitive radio(CR) network where a pair of twoway secondary users(SUs) is allowed to coexist with a primary user(PU) as long as the interference power received at the PU is below an acceptable limit. Under the interference power constraint, we investigate the effective capacity region for two-way SUs. In particular, we derive a closed-form solution for the power allocation problem to achieve the boundary points of an inner bound on the effective capacity region. We also propose a key parameter referred to as weighted-transmission-interference-ratio(WTIR), which plays a significant role in the power allocation policy. In the proposed power allocation policy, the exclusive transmission of SUs shall be performed if one SU’s WTIR is much larger than the others. That is, the one with much larger WTIR shall be allocated non-zero power and the other one shall be allocated zero power. Otherwise, if the difference of their WTIRs is not significant, the concurrent transmission shall be performed. That is, both SUs shall be allocated non-zero power. It is shown that a loose interference power constraint leads to the concurrent transmission in most situations, while a stringent interference power constraint leads to the exclusive transmission in most situations. It is also shown that for the stringent interference power constraint and loose delay quality-of-service(Qo S) constraint, the proposed power allocation policy is almost optimal and thus the obtained inner bound on the effective capacity region is tight.

关键词： cognitive radio effective capacity delay quality-of-service power allocation two-way

Cooperative resource allocation in cognitive wireless powered communication networks with energy accumulation and deadline requirements

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Science China(Information Sciences) 2019年第8期62卷 145-158页

作者： ding xu Qun LI Wireless Communication Key Lab of Jiangsu Province Nanjing University of Posts and Telecommunications Engineering Research Center of Health Service System Based on Ubiquitous Wireless Networks Nanjing University of Posts and Telecommunications

This study investigates a multi-carrier cognitive wireless powered communication network(CWPCN) with a wirelessly powered primary user(PU). A two-stage cooperative protocol between the PU and the secondary user(SU) is adopted so that the PU can harvest energy from the SU while the SU gains transmission opportunities. It is assumed that the energy harvested by the PU can be accumulated for future usage, and the quality of service of the PU is guaranteed by satisfying the required minimum number of data bits for a given deadline. Herein, we maximize the SU rate by considering the time allocation,subcarrier allocation, and power allocation in both an offline setting(in which the future channel gains are known a priori) and an online setting(in which only the current channel gains are known). In the offline and online schemes, the maximization problem is solved using the block-coordinate descent method and the Lagrange duality method. The effectiveness of the proposed schemes is evaluated and verified via simulation experiments against benchmark schemes.

关键词： wireless powered communication networks energy harvesting cognitive radio deadline constraint energy accumulation

Resource allocation in cognitive wireless powered communication networks with wirelessly powered secondary users and primary users

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Science China(Information Sciences) 2019年第2期62卷 224-229页

作者： ding xu Qun LI Wireless Communication Key Lab of Jiangsu Province Nanjing University of Posts and Telecommunications Jiangsu Key Lab of Big Data Security and Intelligent Processing Nanjing University of Posts and Telecommunications

Dear editor,Wireless powered communication networks(WPCNs) are popular especially for wireless sensor networks where sensors can be wirelessly powered. For coordinating wireless power and information transfer, Ju and Zhang in their pioneer work [1] proposed a "harvest-then-transmit" protocol for WPCN, where the time for wireless power transfer (WPT) and wireless information transfer(WIT) is divided into two phases:the WPT phase and WIT phase. Meanwhile, cognitive radio (CR)

关键词： WIT Resource allocation in cognitive wireless powered communication networks with wirelessly powered secondary users and primary users

Proactive eavesdropping of wireless powered suspicious interference networks

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Science China(Information Sciences) 2021年第12期64卷 260-261页

作者： ding xu Hongbo ZHU Wireless Communication Key Lab of Jiangsu Province Nanjing University of Posts and Telecommunications

Dear editor,Radio frequency(RF) energy harvesting is a technology that enables harvesting energy from RF signals, and the wireless powered communication network(WPCN) is a new type of wireless network, where devices are powered by RF energy harvesting [1, 2]. Meanwhile, physical layer security(PLS)is a technique to ensure communication security from the aspect of the physical layer,

关键词： Information Systems and Communication Service

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High Strength Cellulose Composite Films Reinforced with Clay for Applications as Antibacterial Materials

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Chinese Journal of Polymer Science 2016年第10期34卷 1281-1289页

作者： ding-feng xu 蔡杰张俐娜 College of Chemistry & Molecule Sciences Wuhan University Wuhan 430072 China

High strength cellulose composite films with antibacterial activities were prepared by dispersing montmorillonites （MMT） into cellulose solution in LiOH/urea aqueous solvent followed by regeneration in ethanol coagulation bath, and then by soaking in 5 wt% hexadecylpyridine bromide ethanol solutions to induce the antibacterial action. The cellulose/MMT composite films were characterized by field emission scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, FTIR, UV-spectra, wide angle X-ray diffraction and mechanical test. The results revealed that MMT was dispersed well in the cellulose matrix to form layer structure with a thickness of approximately 3 nm. The mechanical properties of the cellulose/MMT composite films were significantly improved to achieve 132 MP for tensile strength as a result of the MMT delamination. The hexadecylpyridine bromide was fixed well in the cellulose/MMT matrix through cation exchange, leading to the excellent antibacterial activities against Staphylococcus aureus and Escherichia coli, which is important in their practical applications.

关键词： Cellulose/MMT composite films Antibacterial activities High strength Hexadecylpyridine bromide.

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Effective capacity of delay quality-of-service constrained spectrum sharing cognitive radio with outdated channel feedback

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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

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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