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| 1 | Flooding attack and defence in Ad hoc networks显示文摘Mobile ad hoc networks are particularly vulnerable to denial of service (DOS) attacks launched through compromised nodes or intruders. In this paper, we present a new DOS attack and its defense in ad hoc networks. The new DOS attack,called Ad hoc Flooding Attack(AHFA), is that intruder broadcasts mass Route Request packets to exhaust the communication bandwidth and node resource so that the valid communication can not be kept. After analyzed Ad hoc Flooding Attack, we develop Flooding Attack Prevention (FAP), a generic defense against the Ad hoc Flooding Attack. When the intruder broadcasts exceeding packets of Route Request, the immediate neighbors of the intruder record the rate of Route Request. Once the threshold is exceeded, nodes deny any future request packets from the intruder. The results of our implementation show FAP can prevent the Ad hoc Flooding attack efficiently. | Yi Ping Hou Yafei Zhong Yiping Zhang Shiyong Dai Zhoulin | 2006 | Journal of Systems Engineering and Electronics2006，17，2： | 5 |
| 2 | Impact of meteorological condition changes on air quality and particulate chemical composition during the COVID-19 lockdown显示文摘Stringent quarantine measures during the Coronavirus Disease 2019(COVID-19)lockdown period(January 23,2020 to March 15,2020)have resulted in a distinct decrease in anthropogenic source emissions in North China Plain compared to the paralleled period of 2019.Particularly,22.7%decrease in NO_(2)and 3.0%increase of O_(3)was observed in Tianjin,nonlinear relationship between O_(3)generation and NO_(2)implied that synergetic control of NOx and VOCs is needed.Deteriorating meteorological condition during the COVID-19 lockdown obscured the actual PM2.5 reduction.Fireworks transport in 2020 Spring Festival(SF)triggered regional haze pollution.PM2.5 during the COVID-19 lockdown only reduced by 5.6%in Tianjin.Here we used the dispersion coefficient to normalize the measured PM2.5(DN-PM2.5),aiming to eliminate the adverse meteorological impact and roughly estimate the actual PM2.5 reduction,which reduced by 17.7%during the COVID-19 lockdown.In terms of PM2.5 chemical composition,significant NO_(3)−increase was observed during the COVID-19 lockdown.However,as a tracer of atmospheric oxidation capacity,odd oxygen(Ox=NO_(2)+O_(3))was observed to reduce during the COVID-19 lockdown,whereas relative humidity(RH),specific humidity and aerosol liquid water content(ALWC)were observed with noticeable enhancement.Nitrogen oxidation rate(NOR)was observed to increase at higher specific humidity and ALWC,especially in the haze episode occurred during 2020SF,high air humidity and obvious nitrate generation was observed.Anomalously enhanced air humidity may response for the nitrate increase during the COVID-19 lockdown period. | Jing Ding Qili Dai Yafei Li Suqin Han Yufen Zhang Yinchang Feng | 2021 | Journal of Environmental Sciences2021，33，11： | 2 |
| 3 | User-experience-based availability analysis model and its application in P2P storage systems显示文摘Data availability is one of the most important properties of peer-to-peer (P2P) storage systems.Availability analysis model and data placement are two key design choices.Users in P2P storage system are both providers and customers.This characteristic determines that the availability analysis must be user-centric,and thereby enhance the quality of service and decrease the system cost.The popular approach in recent studies is simple random placement with steady-state model,which has the following drawbacks:1) It ignores the up/down patterns of nodes,whose availability is over-estimated or under-estimated at different periods of time.2) It ignores the access patterns of users,so the availability perceived by users is hard to evaluate precisely.3) It ignores the huge difference of nodes' availability, thus leading to the absence of incentive. This paper proposes a novel user-experience-based availability model, which evaluates the availability of P2P storage system in terms of user experience,which can degenerate to traditional availability analysis model. Based on the new model,this paper proposes decentralized data placement algorithms for two typical P2P storage applications:'data sharing'and'personal backup'.By the trace-driven simulation, we prove that our methods can enhance the availability perceived by users greatly,reduce the variance of the availability dramatically and eliminate the nodes with low availability in data-sharing applications;meanwhile,it can provide different-level service to encourage users according to their contributions. | WU Yu YANG Zhi QU Zhi XIAO Zhen DAI YaFei | 2011 | Science China(Information Sciences)2011，54，8： | 2 |
| 4 | A multiple user sharing behaviors based approach for fake file detection in P2P environments显示文摘File pollution is a problem that is threatening security and availability in peer-to-peer environments, and could eventually be fatal to the survival of these systems. Current methods of fake file detection, which are based on trust mechanisms or file characteristics, do not consider the problems such as interference of multiple user sharing behaviors, the difficulty in obtaining large amounts of raw data, and malicious fraud immediately after version publication. This is the first time that differences in the sharing habits of users and particularly long retention time for individual files have been detected, which impact fake file detection. This paper proposes a pollution prevention model based on multiple user sharing behaviors, which reduces interference in multiple user sharing behaviors and malicious fraud immediately after version publication. It designs a low-cost implementation mechanism for use in structured peer-to-peer networks, which automatically collects a large amount of user file-sharing information and alleviates difficulties in obtaining large quantities of raw data. A parameter configuration is also given in this paper. Simulation experiments use realistic system logs and prove that this approach detects fake files accurately and quickly, thus decreasing download times of fake files, effectively guaranteeing almost 100% real file downloads and resisting file pollution. | JIANG Jing, LI YongJun, FENG QinYuan, HUANG Peng & DAI YaFei Department of Computer Science and Technology, Peking University, Beijing 100871, China | 2010 | Science China(Information Sciences)2010，53，11： | 1 |
| 5 | A monoclonal antibody targeting neuropilin-1 inhibits adhesion of MCF7 breast cancer cells to fibronectin by suppressing the FAK/p130cas signaling pathway显示文摘 | Fanwei Zeng Fanghong Luo Sha Lv Haipeng Zhang Chang Cao Xiaoli Chen Shengyu Wang Zhe Li Xianjiang Wang Xiaofeng Dou Yujuan Dai Mingjun He Yafei Zhang Haiyan Lv Jianghua Yan Yuqiang Chen | 2014 | Anti-Cancer Drugs2014，，： | 1 |
| 6 | An implementation and optimization for scalable DHT crawler显示文摘KAD is one of the largest scale DHT based on real applications. Measurements on KAD is a good approach for researching DHT. Many different active and passive measurements have been made on those systems, and crawlers are novel approach in active measurement. A crawler begins crawling into the DHT with a basic set of given nodes, sending node searching requests to the nodes in the given set for contact information from more unknown nodes. There are three goals in mind while we design the crawler: finishing crawling the given nodes set as soon as possible; retrieving more nodes information after the crawling; getting result while sending as few network packets as possible. The above goals are correlated with each other. Optimizing one may impact others. This paper proposes a basic DHT crawler framework and discusses possible extension to the framework. After that we exploit the fact that the connectivity in the overlay network is universality, thus we do not need to crawl the whole overlay network space while maintaining the crawling affect. | ZHOU Mo ZHANG JianYu DAI YaFei | 2010 | Science China(Information Sciences)2010，53，4： | 1 |
| 7 | Coarse-Grained Cloud Synchronization Mechanism Design May Lead to Severe Traffic Overuse显示文摘In recent years, cloud sync(hronization) services such as GoogleDrive and Dropbox have provided Internet users with convenient and reliable data storing/sharing functionality. The cloud synchronization mechanism (in particular, how to deliver the user-side data updates to the cloud) plays a critical role in cloud sync services because it greatly affects the cloud operation cost (in terms of sync traffic) and user experience (in terms of sync delay). By comprehensively measuring tens of popular cloud sync services, we find that their cloud sync mechanisms differ greatly in sync performance and design granularity. Quite surprisingly, some very popular services (like GoogleDrive and 115 SyncDisk) utilize a quite coarse-grained cloud sync mechanism that may lead to severe traffic overuse. For example, updating 1-MB data may sometimes result in 260-MB sync traffic. In this paper, we conduct a comparative study of various cloud sync mechanisms by analyzing their respective pros and cons under different situations, unravel the pathological processes for their traffic overuse problems, and finally provide insights/solutions for better choosing/designing a cloud sync service. | Zhenhua Li Zhi-Li Zhang Yafei Dai | 2013 | Tsinghua Science and Technology2013，18，3： | 0 |
| 8 | Beehive: low-cost content subscription service using cloudlets显示文摘In recent years, Content Subscription Service (CSS) is showing a notable success in helping users fetch unpopular data in P2P networks. It works by maintaining a storage pool to pull the subscribed file and then redistribute them to the requestor. However, existing commercial CSS incurs huge bandwidth/equipment cost due to introducing a third-party cloud storage. We present Beehive, a low-cost yet efficient CSS, which leverages the idle node bandwidth/storage (i.e., cloudlets) in the original P2P system to form an inherent cloudlet storage. Since P2P nodes are geographically distributed, highly dynamic and heterogeneous, Beehive adopts three key techniques to achieve high performance. First, by applying random linear network coding, multiple seeders can upload the same file simultaneously without complicated wide-area coordination. Second, a model is developed to set the coding parameters so that the cloudlet storage achieves guaranteed performance in file availability and data distribution efficiency. Finally, by performing task outsourcing, overloaded seeders quickly offload their tasks to idle peers, which effectively balances the load and utilizes the system resources. We implement Beehive with 29,000 lines of C++ codes and deploy it in a real P2P file-sharing system. Results show that Beehive improves the success ratio of pulling peer-side files from 38.7% (traditional online download) to 84.3% (users offline waiting for less than three days), and provides users with over 200 kB/s download speed. | XING YuanJian YANG Zhi CHEN Chi DAI YaFei | 2013 | Science China(Information Sciences)2013，56，7： | 0 |
| 9 | Computer Science Department, Peking University, Beijing 100871, China显示文摘 | YANG Zhi & DAI YaFei | 2011 | Science China(Information Sciences)2011，54，6： | 0 |
| 10 | The complete and fully-phased diploid genome of a male Han Chinese显示文摘Since the release of the complete human genome,the priority of human genomic study has now been shifting towards closing gaps in ethnic diversity.Here,we present a fully phased and well-annotated diploid human genome from a Han Chinese male individual(CN1),in which the assemblies of both haploids achieve the telomere-to-telomere(T2T)level.Comparison of this diploid genome with the CHM13 haploid T2T genome revealed significant variations in the centromere.Outside the centromere,we discovered 11,413 structural variations,including numerous novel ones.We also detected thousands of CN1 alleles that have accumulated high substitution rates and a few that have been under positive selection in the East Asian population.Further,we found that CN1 outperforms CHM13 as a reference genome in mapping and variant calling for the East Asian population owing to the distinct structural variants of the two references.Comparison of SNP calling for a large cohort of 8869 Chinese genomes using CN1 and CHM13 as reference respectively showed that the reference bias profoundly impacts rare SNP calling,with nearly 2 million rare SNPs miss-called with different reference genomes.Finally,applying the CN1 as a reference,we discovered 5.80 Mb and 4.21 Mb putative introgression sequences from Neanderthal and Denisovan,respectively,including many East Asian specific ones undetected using CHM13 as the reference.Our analyses reveal the advances of using CN1 as a reference for population genomic studies and paleo-genomic studies.This complete genome will serve as an alternative reference for future genomic studies on the East Asian population. | Chentao Yang Yang Zhou Yanni Song Dongya Wu Yan Zeng Lei Nie Panhong Liu Shilong Zhang Guangji Chen Jinjin Xu Hongling Zhou Long Zhou Xiaobo Qian Chenlu Liu Shangjin Tan Chengran Zhou Wei Dai Mengyang Xu Yanwei Qi Xiaobo Wang Lidong Guo Guangyi Fan Aijun Wang Yuan Deng Yong Zhang Jiazheng Jin Yunqiu He Chunxue Guo Guoji Guo Qing Zhou Xun Xu Huanming Yang Jian Wang Shuhua Xu Yafei Mao Xin Jin Jue Ruan Guojie Zhang | 2023 | Cell Research2023，33，10： | 0 |
| 11 | Thermal safety boundary of lithium-ion battery at different state of charge显示文摘Thermal runaway(TR)is a critical issue hindering the large-scale application of lithium-ion batteries(LIBs).Understanding the thermal safety behavior of LIBs at the cell and module level under different state of charges(SOCs)has significant implications for reinforcing the thermal safety design of the lithium-ion battery module.This study first investigates the thermal safety boundary(TSB)correspondence at the cells and modules level under the guidance of a newly proposed concept,safe electric quantity boundary(SEQB).A reasonable thermal runaway propagation(TRP)judgment indicator,peak heat transfer power(PHTP),is proposed to predict whether TRP occurs.Moreover,a validated 3D model is used to quantitatively clarify the TSB at different SOCs from the perspective of PHTP,TR trigger temperature,SOC,and the full cycle life.Besides,three different TRP transfer modes are discovered.The interconversion relationship of three different TRP modes is investigated from the perspective of PHTP.This paper explores the TSB of LIBs under different SOCs at both cell and module levels for the first time,which has great significance in guiding the thermal safety design of battery systems. | Hang Wu Siqi Chen Yan Hong Chengshan Xu Yuejiu Zheng Changyong Jin Kaixin Chen Yafei He Xuning Feng Xuezhe Wei Haifeng Dai | 2024 | Journal of Energy Chemistry2024，91，4： | 0 |
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