检索结果-南通市图书馆

Precoding with interference suppression sequence scheme for OFDM-based cognitive radio systems

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2011年第4期18卷 59-64页

作者： zhao cheng-lin ZHANG Kun SUN Xue-bin JIANG Ting Key Laboratory of Universal Wireless Communication Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

Orthogonal frequency division multiplexing （OFDM） is considered to be one of the promising schemes for cognitive radios （CR） systems, due to its flexibility in spectrum shaping. However, the traditional way of spectrum-notching failed to suppress out-of-band leakage enough, resulting in interference with licensed users （LUs）. A novel spectrum shaping scheme is proposed in this article, where a precoder with interference suppression sequence （ISS） is for the first time introduced for shaping the spectrum of OFDM signals in OFDM-based CR systems. The precoder matrix together with ISS matrix is obtained by minimizing the power of out-of-band interference, which results in the sufficient interference suppression of OFDM signal to LUs Analysis and simulation results show that the proposed scheme can significantly suppress the interference power to LUs at a little cost of precoding efficiency. Meanwhile, the peak-to-average-power-ratio （PAPR） is invariable and the bit-error-rate （BER） performance over Rayleigh fading channel is improved.

关键词： OFDM cognitive radio precoding spectrum shaping

Study on coexistence between DCS1800 and TDD-LTE systems in multi-mode terminals

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2014年第6期21卷 24-29页

作者： ZHENG Zhi-hui zhao cheng-lin Li Bin TAO Hong-bo School of Telecommunication Engineering Beijing University of Posts and Telecommunications The State Radio Monitoring Center Testing Center

It＇s well known that the mobile stations will comprise a wide range of radio access technologies（RAT）, providing user with flexible and efficient access to multi-media service and high data rate communications. Although much work has been done for coexistence analysis between different systems base stations（BS）, most of them have not addressed the interference within multi-mode terminal. Hence, for filling the gap, The authors in the article present coexistence studyies of digital cellular system at 1 800 MHz（DCS1800） and time division duplex long term evolution（TDD-LTE） network in multi-mode terminal with multi-service provisioning. A new system model for coexistence was introduced and how deterministic analysis can be done within the terminal was explained. The interference evaluation model was given based on relations between reference sensitivity and signal-to-noise ratio（SNR）, which is also deduced. The system simulation methodology was provided and assumption used in simulation was given. Simulation results were shown with different system parameters. Numeric results indicate that multi-mode terminal is mainly affected by local interference. The minimum antenna isolation required for a health system operation was provided.

关键词： TDD-LTE systems coexistence analysis multi-mode terminal deterministic analysis sensitivity degradation

Deepen spectrum notch and reduce PAPR in OFDM systems via combining subcarriers precoding with tone reservation

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2011年第3期18卷 80-84页

作者： zhao cheng-lin LIU De-qiang SUN Xue-bin JIANG Ting School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

In orthogonal frequency division multiplexing （OFDM） systems, spectrum notch can be generated to mitigate interference to other narrow-band services by turning off corresponding subcarriers. However, the inter-carrier interference may limit considerably the produced notch depth. Another problem in OFDM is the high peak-to-average power ratio （PAPR）. In this paper, a technique combining subcarriers precoding with tone reservation is proposed to deepen spectrum notch and simultaneously reduce peak-to-average power ratio. Simulation results show that this presented joint algorithm can produce satisfied results to solve these problems at the expense of a moderate loss in bit error rate （BER） performance.

关键词： OFDM, spectrum notch, PAPP subcarriers precoding, tone reservation

Performance analysis of 3G systems in presence of UWB interference

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2011年第2期18卷 120-124页

作者： SUN Xue-bin GAO Ming-liang ZHOU Zheng zhao cheng-lin LIU Wei School of Telecommunication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China China Mobile Research Institute (China) Beijing 100053 China

In this paper,the impact of the interference from multiple ultra wideband（UWB） transmitters to a 3rd-generation（3G） terminal is evaluated under UWB emission power limit regulations of federal communications commission（FCC）,european telecommunications standards institute（ETSI） and Japan respectively.A three-dimensional interference model is presented where a discrete spatial distribution of UWB transmitters is *** is assumed that a mobile terminal and a large number of UWB devices exist in one room simultaneously.A parameter which characterizes the link budget degradation at the victim receiver is defined to measure the UWB interference to 3G *** maximum acceptable density of UWB transmitters and the minimum acceptable distance between UWB transmitters and the 3G terminal are analyzed under different link budget *** simulation results demonstrate that the performance of time division-synchronous code division multiple access（TD-SCDMA） is the best,the one of code division multiple access 2000（CDMA2000） is the worst and the one of wideband code division multiple access（WCDMA） lies between them in presence of UWB interference.

关键词： UWB TD-SCDMA CDMA2000 WCDMA interference

Research on a TOPSIS energy efficiency evaluation system for crude oil gathering and transportation systems based on a GA-BP neural network

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第1期21卷 621-640页

作者： Xue-Qiang Zhang Qing-lin cheng Wei Sun Yi zhao Zhi-Min Li Key Lab of Ministry of Education for Enhancing the Oil and Gas Recovery Ratio Northeast Petroleum UniversityDaqing163318HeilongjiangChina China Petroleum Pipeline Material and Equipment Co. LtdLangfang065000HebeiChina Research Institute of Petroleum Engineering and Technology Sinopec Northwest Oilfield CompanyUrumqi830011XinjiangChina

As the main link of ground engineering,crude oil gathering and transportation systems require huge energy consumption and complex *** is necessary to establish an energy efficiency evaluation system for crude oil gathering and transportation systems and identify the energy efficiency *** this paper,the energy efficiency evaluation system of the crude oil gathering and transportation system in an oilfield in western China is *** with the big data analysis method,the GA-BP neural network is used to establish the energy efficiency index prediction model for crude oil gathering and transportation *** comprehensive energy consumption,gas consumption,power consumption,energy utilization rate,heat utilization rate,and power utilization rate of crude oil gathering and transportation systems are *** the efficiency and unit consumption index of the crude oil gathering and transportation system,the energy efficiency evaluation system of the crude oil gathering and transportation system is established based on a game theory combined weighting method and TOPSIS evaluation method,and the subjective weight is determined by the triangular fuzzy analytic hierarchy *** entropy weight method determines the objective weight,and the combined weight of game theory combines subjectivity with objectivity to comprehensively evaluate the comprehensive energy efficiency of crude oil gathering and transportation systems and their ***,the weak links in energy utilization are identified,and energy conservation and consumption reduction are *** above research provides technical support for the green,efficient and intelligent development of crude oil gathering and transportation systems.

关键词： Crude oil gathering and transportation system GA-BP neural network Energy efficiency evaluation TOPSIS evaluation method Energy saving and consumption reduction

Exogenous calcium enhances the physiological status and photosynthetic capacity of rose under drought stress

在线全文

学校读者我要写书评

暂无评论

Horticultural Plant Journal 2024年第3期10卷 853-865页

作者： Xiaojuan zhao Shang lin Shuang Yu Yichang Zhang lin Su Lifang Geng Chenxia cheng Xinqiang Jiang College of Landscape Architecture and Forestry Qingdao Agricultural UniversityQingdaoShandong 266000China College of Horticultural Qingdao Agricultural UniversityQingdaoShandong 266000China

Drought(water shortage)can substantially limit the yield and economic value of rose plants(Rosa spp.).Here,we characterized the effect of exogenous calcium(Ca^(2+))on the antioxidant system and photosynthesis-related properties of rose under polyethylene glycol 6000(PEG6000)-induced drought *** levels,as well as leaf and root biomass,were significantly reduced by drought;drought also had a major effect on the enzymatic antioxidant system and increased concentrations of reactive oxygen *** of exogenous Ca^(2+)increased the net photosynthetic rate and stomatal conductance of leaves,enhanced water-use efficiency,and increased the length and width of stomata following exposure to ***-specific physiological responses were observed under different concentrations of Ca^(2+).Application of 5 mmol·L^(-1)Ca^(2+)promoted photosynthesis and antioxidant activity in the leaves,and application of 10 mmol·L^(-1)Ca^(2+)promoted antioxidant activity in the *** of exogenous Ca^(2+)greatly enhanced the phenotype and photosynthetic capacity of potted rose plants following exposure to drought ***,our findings indicate that the application of exogenous Ca^(2+)enhances the drought resistance of roses by promoting physiological adaptation and that it could be used to aid the cultivation of rose plants.

关键词： Rosa hybrida L. Exogenous calcium Drought stress Physiological index Photosynthetic capacity

Magnetic-field-assisted triboelectric nanogenerator for harvesting multi-directional wave energy

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第8期17卷 7144-7152页

作者： Mengru Ding Jianlong Wang Da zhao Hengyu Li Xiaojun cheng Jianming Wen Zhong lin Wang Tinghai cheng Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of SciencesBeijing 101400China School of Nanoscience and Engineering University of Chinese Academy of SciencesBeijing 100049China Guangzhou Institute of Blue Energy Guangzhou 510555China College of Engineering Zhejiang Normal UniversityJinhua 321004China School of Materials Science and Engineering Georgia Institute of TechnologyAtlantaGA 30332-0245USA

Ocean wave energy is a significant and promising source of renewable ***,the energy harvesting is challenging due to the multi-directional nature of *** paper proposes a magnetic-field-assisted triboelectric nanogenerator(MFATENG)for harvesting multi-directional wave *** incorporating a magnetic field,the planar motion of the pendulum is converted into spatial motion,increasing the triggering of multilayered TENG(M-TENG)and enhancing the output energy of the *** results demonstrate that the output energy of the MFA-TENG is increased by 73%by utilizing the magnetic ***,a spring model based on the origami-structured M-TENG is established to analyze the effect of different equivalent stiffnesses on the performance of the M-TENG,aiming to obtain optimal output *** results showcase the impressive output performance of the M-TENG,generating outputs of 250 V,18μA,and 255 ***,the proposed MFA-TENG effectively harvests multi-directional wave energy under water-wave driven *** study significantly enhances the ability of the MFA-TENG to harvest multi-directional wave energy and presents a promising approach for self-powered marine monitoring in the future.

关键词： triboelectric nanogenerator magnetic-field-assisted spring model multi-directional wave energy

The Minimum Centroid Branch Spanning Tree Problem

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of the Operations Research Society of China 2024年第2期12卷 528-539页

作者： Hao lin cheng He School of Science Henan University of TechnologyZhengzhou450001HenanChina

For a spanning tree T of graph G,the centroid of T is a vertex v for which the largest component of T-v has as few vertices as *** number of vertices of this component is called the centroid branch weight of *** minimum centroid branch spanning tree problem is to find a spanning tree T of G such that the centroid branch weight is *** application to design of communication networks,the loads of all branches leading from the switch center should be as balanced as *** this paper,we prove that the problem is strongly NP-hard even for bipartite ***,the problem is shown to be polynomially solvable for split graphs,and exact formulae for special graph familis,say Kn_(1),n_(2),...,n_(k)and P_(m)×P_(n),are presented.

关键词： Spanning tree optimization Centroid branch-NP-hardness Polynomial-time algorithm

Anti-inflammatory mechanism of the non-volatile ingredients performance liquid chromatography-heated electron spray ionization-high resolution mass spectroscope and cell metabolomics

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Traditional Chinese Medicine 2024年第2期44卷 260-267页

作者： JING Wenguang lin Xiaoyu LI Chu zhao Xiaoliang cheng Xianlong WANG Penglong WEI Feng MA Shuangcheng Institute of Control of Chinese Traditional Medicine and Ethnic Medicine National Institutes for Food and Drug ControlBeijing 102629China School of Traditional Chinese Medicine Beijing University of Chinese MedicineBeijing 102488China Beijing Key Laboratory of Traditional Chinese Medicine Basic Research on Prevention and Treatment of Major Diseases Experimental Research CenterChina Academy of Chinese Medical SciencesBeijing 100700China

OBJECTIVE:To explore the anti-inflammatory components and mechanism of the non-volatile ingredients of ***:High performance liquid chromatographyheated electron spray ionization-high resolution mass spectroscope(HPLC-HESI-HRMS)was used to analyze the chemical constituents of the non-volatile ingredients of *** anti-inflammatory activity of ingredients was evaluated using lipopolysaccharide(LPS)induced RAW264.7 cell inflammation model,and the antiinflammatory mechanism was investigated using multivariate statistical analysis of cell ***:The non-volatile ingredients of patchouli were characterized by HPLC-HESI-HRMS,and 36 flavonoids and 18 other components were *** ingredients of patchouli not only had a good protective effect on the LPS-induced inflammation model of RAW264.7 cells,but also regulated the expression levels of arginine,L-leucine,cholesterol,fructose and sorbitol by down-regulating arginine metabolism,aminoacyl-tRNA biosynthesis,polyol/sorbitol pathway,so as to reduce inflammation and reduce cell ***:The non-volatile ingredients of patchouli had good anti-inflammatory effect and exerted its curative effect by regulating endogenous metabolic pathway to reduce inflammatory response.

关键词： Pogostemon non-volatile ingredients anti-inflammatory cell metabolomics