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Cartan-Eilenberg iV-complexes with respect to self-orthogonal subcategories

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Frontiers of Mathematics in China 2020年第2期15卷 351-365页

作者： Bo LU Zhenxing DI yifu liu College of Mathematics and Computer Science Northwest Minzu UniversityLanzhou 730030China Department of Mathematics Northwest Normal UniversityLanzhou 730070China

Let R be an arbitrary associated *** an integer N≥2 and a self-orthogonal subcategory W of R-modules,we study the notion of Cartan-Eilenberg W *** show that an N-complex X is Cartan-Eilenberg W if and only if X≌X′■X″in which X′is a W iV-complex and X″is a graded/7-module with X″n∈W for all n∈*** applications of the result,we obtain some characterizations of Cartan-Eilenberg projective and injective N-complexes,establish Cartan and Eilenberg balance of N-complexes,and give some examples for some fixed integers N to illustrate our main results.

关键词： Cartan-Eilenberg W N-complex,Cartan-Eilenberg projective N-complex Cartan-Eilenberg injective TV-complex Cartan-Eilenberg balance

Optimized beaconing rate control for vehicular Ad-hoc networks

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The Journal of China Universities of Posts and Telecommunications 2015年第6期22卷 10-17,50页

作者： Tang Lun liu yifu Chen Qianbin Key Laboratory of Mobile Communication Technology Chongqing University of Posts and Telecommunications

In vehicular Ad-hoc networks （VANETs）, beacon message is designed for the purpose of periodically broadcasting the status information （velocity, direction, etc.）, which enable neighbor awareness and support some safety applications. However, under high density scenarios, fixed rate beaconing can cause severe congestion and lower the deliver rate of beacons and other kinds of messages. In this paper, we describe beaconing rate control approach with an one-dimensional Markov model, and based on this, an optimized beacon rate control scheme is proposed which aims to mitigate the congestion and maximize the deliver efficiency of beaconing. Analytical and simulation results show that our proposed scheme can achieve higher adaptability and beaconing efficiency compared with other schemes in various environments.

关键词： VANETs IEEE 802.1 lp broadcast beacon rate control optimization model

联合VMD和Bi-LSTM的GNSS坐标时序降噪

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测绘科学 2024年第1期49卷 23-32页

作者：刘逸夫徐克科郭增长张子豪河南理工大学测绘与国土信息工程学院河南焦作454003 河南测绘职业学院郑州451464

针对GNSS坐标时间序列中的噪声难以有效去除等问题,构建了一种联合变分模态分解和双向长短期记忆模型的方法用以去除GNSS坐标时间序列中的噪声。将GNSS坐标时间序列分解为k个本征模态函数分量,并根据样本熵选择出有效的模态分量,分别通... 详细信息

针对GNSS坐标时间序列中的噪声难以有效去除等问题,构建了一种联合变分模态分解和双向长短期记忆模型的方法用以去除GNSS坐标时间序列中的噪声。将GNSS坐标时间序列分解为k个本征模态函数分量,并根据样本熵选择出有效的模态分量,分别通过双向长短期记忆网络处理,最后将信号进行合成。以BJFS等12个具有较长时间序列且数据完整性较好的GNSS站点坐标数据为例,对坐标时间序列进行降噪。将该方法与传统的分解方法进行对比分析,发现在E、N、U方向上,相比于单一变分模态分解,速度不确定度改正率分别提高了11.03%、4.60%、7.39%,相比于经验模态分解分别提高了31.70%、27.70%、24.42%。结果表明该方法能够更好地去除信号中的噪声,且优于传统分解方法,可提高信号可靠性。

关键词： GNSS坐标时间序列变分模态分解双向长短期记忆样本熵信号降噪

Another Gorenstein Analogue of Projective Complexes

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Wuhan University Journal of Natural Sciences 2020年第6期25卷 477-482页

作者： LU Bo liu yifu College of Mathematics and Computer Science Northwest Minzu UniversityLanzhou 730030Gansu

As we know,a complex P is projective if and only if P is exact with Z_n(P)projective in R-Mod for each n∈Z and any morphism f:P→C is null homotopic for any complex *** this article,we study the notion of DG-Gorenstein projective *** show that a complex G is DG-Gorenstein projective if and only if G is exact with Z_n(G)Gorenstein projective in R-Mod for each n∈Z and any morphism f:G→Q is null homotopic whenever Q is a DG-projective complex.

关键词： Gorenstein projective module DG-projective complex DG-Gorenstein projective complex

不同温度下PYX在3种溶剂中的结晶形貌预测

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中北大学学报（自然科学版） 2024年第1期45卷 83-89页

作者：雷超刚吕天成胡立双刘洋张添淇刘逸夫王慧男中北大学环境与安全工程学院山西太原030051 湖北航鹏化学动力科技有限责任公司湖北襄阳441003

本文应用分子动力学模拟方法,模拟了2,6-二苦氨基-3,5-二硝基吡啶(PYX)在真空中的晶体形貌。通过计算溶剂和晶面之间的相互作用能,修正了附着能,模拟出5种温度条件下PYX在3种溶剂(二甲基亚砜(DMSO)、N,N-二甲基甲酰胺(DMF)、N-甲基吡咯... 详细信息

本文应用分子动力学模拟方法,模拟了2,6-二苦氨基-3,5-二硝基吡啶(PYX)在真空中的晶体形貌。通过计算溶剂和晶面之间的相互作用能,修正了附着能,模拟出5种温度条件下PYX在3种溶剂(二甲基亚砜(DMSO)、N,N-二甲基甲酰胺(DMF)、N-甲基吡咯烷酮(NMP))中的晶体形貌。结果表明:PYX在真空条件下主要显露的3个晶面分别是(0 1 1)晶面、(1 0 1)晶面、(1 1 0)晶面,总面积占比为95.975%,PYX在真空中的晶体形貌是较为规整的多面体,纵横比为1.388。PYX各晶面与3种不同溶剂的相互作用能差异较大,导致各晶面修正附着能的差异较大,而且不同温度对晶面能量的影响也较显著,导致形貌各不相同。其中,298 K时NMP溶剂的作用和418 K时DMF溶剂的作用,均促使PYX呈现出类球体,纵横比分别是1.311和1.322,为制备PYX球晶提供方向。

关键词：耐热炸药 2,6-二苦氨基-3,5-二硝基吡啶(PYX) 温度晶体形貌分子动力学

Diversity Analysis of Chlorophyll, Flavonoid, Anthocyanin, and Nitrogen Balance Index of Tea Based on Dualex

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Phyton-International Journal of Experimental Botany 2021年第5期90卷 1549-1558页

作者： yifu liu Jiazhen Wang Yao Xiao Xiongwen Shi Yixia Zeng College of Biology and Agriculture Science and Technology Zunyi Normal UniversityZunyi563000China Tea Research Institute Zunyi Normal UniversityZunyi563000China

The chemical compositions of tea(Camellia sinensis)are affected by numerous factors,such as cultivar,climate,leaf position,and cultivation ***,under the same conditions,the chemical compositions are mainly determined by ***,we investigated the genetic diversity of chemical compositions of tea tree resources in China to screen excellent germplasm *** chemical compositions index(including chlorophyll index,flavonoid index,and anthocyanin index)and the nitrogen balance index of tea leaves were measured in 102 tea germplasms planted in Chinese Tea Plants Improved Variety Germplasm Resources Nursery(CTPIVGRN)by Dualex on April *** showed that the chlorophyll,flavonoid,and anthocyanin contents and the nitrogen balance index significantly differed between the 102 tea *** genetic diversity index values were 2.005,2.246,1.599,and 1.838,and the average genetic diversity was *** 102 tea germplasms can be divided into four categories by cluster analysis under the genetic distance threshold of *** results suggest that the genetic diversity of tea germplasm resources in China is *** study’s results can serve as a basis for the diversified development and utilization of tea plant.

关键词： Tea nitrogen balance index diversity chlorophyll anthocyanin flavonoid

DDoS Attack Detection via Multi-Scale Convolutional Neural Network

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Computers, Materials & Continua 2020年第3期62卷 1317-1333页

作者： Jieren Cheng yifu liu Xiangyan Tang Victor SSheng Mengyang Li Junqi Li School of Information Science and Technology Hainan University570228HaikouChina State Key Laboratory of Marine Resource Utilization in South China Sea 570228HaikouChina Department of Computer Science University of Central ArkansasConwayAR 72035USA

Distributed Denial-of-Service(DDoS)has caused great damage to the network in the big data *** methods are characterized by low computational efficiency,high false alarm rate and high false alarm *** this paper,we propose a DDoS attack detection method based on network flow grayscale matrix feature via multi-scale convolutional neural network(CNN).According to the different characteristics of the attack flow and the normal flow in the IP protocol,the seven-tuple is defined to describe the network flow characteristics and converted into a grayscale feature by *** on the network flow grayscale matrix feature(GMF),the convolution kernel of different spatial scales is used to improve the accuracy of feature segmentation,global features and local features of the network flow are extracted.A DDoS attack classifier based on multi-scale convolution neural network is *** show that compared with correlation methods,this method can improve the robustness of the classifier,reduce the false alarm rate and the missing alarm rate.

关键词： DDoS attack detection convolutional neural network network flow feature extraction

Riverine sulfate sources and behaviors in arid environment,Northwest China:Constraints from sulfur and oxygen isotopes

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Journal of Environmental Sciences 2024年第3期137卷 716-731页

作者： yifu Xu Wenjing liu Bing Xu Zhifang Xu Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

The fate of riverine sulfate ion (SO_(4)^(2-)) and its environmental effects in arid environment are difficult to evaluate due to its complicated sources and strongly coupled behaviors with water cycle which is significantly modified by *** understand the sulfur cycle in aquatic systems in arid environment,the chemical and sulfur and oxygen isotopic compositions (δ^(34)S_(SO4)and δ^(18)O_(SO4)) of major rivers around the Badain Jaran Desert,northwestern China,were *** rivers had averaged SO_(4)^(2-)content at 1336μmol/L,over 10times higher than the global *** δ^(34)S_(SO4)and δ^(18)O_(SO4)values ranged from-5.3‰to+11.8‰and+1.6‰to+12.8‰,*** end-member analysis and the inverse model showed that riverine sulfate was mainly derived from evaporites dissolution (0-87%),sulfide oxidation (13%-100%) and precipitation (0-33%),indicating heterogeneity in sulfur sources and behaviors along the river drainage with the lithology variations and climate *** isotopic tools combining with hydro-chemistry compositions could be applied to reveal sulfur cycle in arid *** on the calculation,sulfide oxidation plays the primary role in the headwater and upstream in the Qilian-Mountains area,where sulfide is widely *** the proportion of evaporites dissolution contributing to riverine sulfate is much higher in downstream in a drier ***,less precipitation and higher temperature can lead to more intensive evaporation,affecting the process of sulfide oxidation and enhancing the rates of evaporites dissolution and sulfate precipitation in the basin.

关键词： Sulfur and oxygen isotopes Source apportionment Inverse model Arid environment Inland rivers Northwestern China

Tailoring NH4+ storage by regulating oxygen defect in ammonium vanadate

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Green Energy & Environment 2024年第7期9卷 1171-1182页

作者： Yanyan liu Ziyi Feng Hanmei Jiang Xueying Dong Changgong Meng yifu Zhang State Key Laboratory of Fine Chemicals School of Chemical Engineering Dalian University of Technology College of Environmental and Chemical Engineering Dalian University

Defect engineering is an effective strategy for modifying the energy storage materials to improve their electrochemical ***, the impact of oxygen defect and its content on the electrochemical performances in the burgeoning aqueous NH+4storage field remains explored. Therefore, for the first time in this work, an oxygen-defective ammonium vanadate [（NH4）2V10O25·8H2O, denoted as Od-NHVO] with a novel 3D porous flower-like architecture was achieved via the reduction of thiourea in a mild reaction condition, which is a facile method that can realize the intention to regulate the oxygen defect content, with the capability of mass-production. The as-prepared OdM-NHVO with moderate oxygen defect content can deliver a stable specific capacitance output(505 F g-1, 252 mAh g-1at 0.5 A g-1with ～80% capacitance retention after 10,000 cycles), which benefits from extra active sites, unimpeded NH+4-migration path and relatively high structure integrity. In contrast, low oxygen defect content will lead to the torpid electrochemical reaction kinetics while too high content of it will reduce the chargestorage capability and induce structural disintegration. The superior NH+4-storage behavior is achieved with the reversible intercalation/deintercalation process of NH+4accompanied by forming/breaking of hydrogen bond. As expected, the assembled flexible OdM-NHVO//PTCDI quasi-solid-state hybrid supercapacitor（FQSS HSC） also exhibits high areal capacitance, energy density and reliable flexibility. This work provides a new avenue for developing materials with oxygen-deficient structure for application in various aqueous non-metal cation storage systems.

关键词： Ammonium vanadate Oxygen defect Ammonium-ion storage Hybrid supercapacitors Electrochemical performance