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An underwater acoustic direct sequence spread spectrum communication system using dual spread spectrum code

Frontiers of Information Technology & Electronic Engineering 2018年第8期19卷 972-983页

作者： Lan-jun liU jian-fen li lin ZHOU Peng ZHAI Hao ZHAO Jiu-cai JIN Zhi-chao LV College of Engineering Ocean University of China The First Institute of Oceanography State Oceanic Administration College of Underwater Acoustic Engineering Harbin Engineering University

With the goal of achieving high stability and reliability to support underwater point-to-point communications and code division multiple access(CDMA) based underwater networks, a direct sequence spread spectrum based underwater acoustic communication system using dual spread spectrum code is proposed. To solve the contradictions between the information data rate and the accuracy of Doppler estimation, channel estimation, and frame synchronization, a data frame structure based on dual spread spectrum code is designed. A long spread spectrum code is used as the training sequence, which can be used for data frame detection and synchronization, Doppler estimation, and channel estimation. A short spread spectrum code is used to modulate the effective information data. A delay cross-correlation algorithm is used for Doppler estimation, and a correlation algorithm is used for channel estimation. For underwater networking, each user is assigned a different pair of spread spectrum codes. Simulation results show that the system has a good anti-multipath, anti-interference, and anti-Doppler performance, the bit error rate can be smaller than 10^(-6) when the signal-to-noise ratio is larger than-10 dB, the data rate can be as high as 355 bits/s, and the system can be used in the downlink of CDMA based networks.

关键词： Underwater acoustic communication Direct sequence spread spectrum Doppler estimation and compensation Channel estimation and equalization Gold code Single carrier Code division multiple access

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Quantitative relationship between surface sedimentary diatoms and water depth in North-Central Bohai Bay,China

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China Geology 2023年第1期6卷 61-69页

作者： Zhi-wen Shang jian-fen li Holger Freund Pei-xin Shi Hong Wang Tianjin Centre China Geological SurveyMinistry of Natural ResourcesTianjin 300170China Key Laboratory of Coast Geo-environment China Geological SurveyMinistry of Natural ResourcesTianjin 300170China Institute of Chemistry and Biology of the Marine Environment Carl von Ossietzky University of OldenburgOldenburg 26111Germany

To study the quantitative relationship between surface sedimentary diatoms and water depth,67 surface samples were collected for diatom analysis on eight profiles with water depth variation from the muddy intertidal zone to the shallow sea area in North-Central Bohai Bay,*** results showed that the distribution of diatoms changed significantly in response to the change in water ***,the quantitative relationship between the distribution of dominant diatom species,their assemblages,and the water depth was *** water depth optima for seven dominant species such as Cyclotella striata/stylorum,Paralia sulcata,and Coscinodiscus perforatus and the water depth indication range of seven diatom assemblages were obtained in the study area above the water depth(elevation)of-10 *** quantitative relationship between surface sedimentary diatoms and water depth provides a proxy index for diatom-paleo-water depth reconstruction in the strata in Bohai Bay,China.

关键词： Diatom Surficial sediments Water depth(elevation) Quantitative relationship Sea level change Paleo-environment change Marine geological survey engineering North-central Bohai Bay China

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The impact of sea-level rise on the coast of Tianjin-Hebei,China

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China Geology 2019年第1期2卷 26-39页

作者： Fu Wang jian-fen li Pei-xin Shi Zhi-wen Shang Yong li Hong Wang Tianjin Center China Geological SurveyMinistry of Natural ResourcesTianjin 300170China Key Laboratory of Muddy Coast Geo-Environment China Geological SurveyMinistry of Natural ResourcesTianjin 300170China

Bulletins of China's National Sea Level show that the average rising rate of sea-levels in China is 3.3 mm/a over the past 40 years, with an obviously accelerated rising trend in the last decade. The rate of relative sea-level rise of the Yangtze River Delta reached >10 mm/a after considering the land subsidence, and Bohai Bay is even greater than 25 mm/a. The impact of the sea level rise to the coastal area will be greater in the coming years, so carrying out an assessment of this rising trend is urgent. This paper, taking the coastal area of Tianjin and Hebei as examples, comprehensively evaluates the impact of sea-level rise through multitemporal remote sensing shoreline interpretation, ground survey verification, elevation measurements for both seawall and coastal lowlands. The results show that the average elevation of the measured coastal areas of Tianjin and Hebei is about +4 m, and the total area of >100 km^2 is already below the present mean sea level. More than 270 km, ca. 31% of the total length of the seawall, cannot withstand a 1-in-100-year storm surge. Numerical simulations of the storm flooding on the west coast of Bohai Bay, for 1-in-50-years, 1-in-100-years, 1-in-200-years and 1-in-500-years, show that if there were no coastal dykes, the maximum flooding area would exceed 3000 km^2, 4000 km^2, 5300 km^2 and 7200 km^2, respectively. The rising sea has a direct and potential impact on the coastal lowlands of Tianjin and Hebei. Based on the latest development in international sea-level rise prediction research, this paper proposes 0.5 m, 1.0 m and 1.5 m as low, middle and high sea level rise scenarios by 2100 for the study area, and combines the land subsidence and other factors to the elevation of the existing seawall. Comprehensive evaluation results indicate that even in the case of a low scenario, the existing seawall will not be able to withstand a 1-in-100-years storm surge in 2030, and the potential flooding areas predicted by the model will be

关键词： Sea level rise Elevation Seawall Shoreline Tianjin-Hebei (Jin-Ji) coast

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Theoretical studies on structure-property relationships of cellulose and nitrocellulose ***,stability and conductivity

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Chinese Journal of Chemistry 1990年第5期8卷 390-395页

作者： XIAO,He-Ming FAN,jian-fen li,Yong-Fu East China Institute of Technology,Nanjing 210014 East China Institute of Technology Nanjing 210014

The banding and electronic structures of a series of long-chain macromolecules of cellu- lose,2-,3-,6-mononitrocellulose,2,3-,2,6-,3,6-dinitrocellulose and trinitrocellulose as well as their structural units(***-,double-or three-ring systems)have been calculated by both the EH and CNDO/2 *** increase of molecular total energies is consistent with the decrease of their stabilities at the three conformations of gg,gt and *** Mulliken bond order of O—NO_2 bond is the samllest in each molecule at any of the three conformations,which indicates that this bond is the weakest,and supports the view of initial homolytic cleavage of O—NO_2 bond on slow thermal *** band gap at the edge of the first Brillouin zone far surpasses 5 eV for cellu- lose,and is less than 3 eV for mono-,di-,and *** results show that cellulose is a typical insulator,as we know,and it can be predicted that nitrocellulose has electric conductivity similar to that of semiconductor.

关键词： Theoretical studies on structure-property relationships of cellulose and nitrocellulose I.Conformation stability and conductivity

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Manipulating the Phase Transition Behavior of Dual Temperature-Responsive Block Copolymers by Adjusting Composition and Sequence

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Chinese Journal of Polymer Science 2024年第2期42卷 176-187,I0006页

作者： Zhi Zou Xiang Xu Hai-Tao Zhao jian-Nan Cheng Wei-Wei He li-fen Zhang Zhen-Ping Cheng Suzhou key Laboratory of Macromolecular Design and Precision Synthesis Jiangsu Key Laboratory of Advanced Functional Polymer Design and ApplicationState and Local Joint Engineering Laboratory for Novel Functional Polymeric MaterialsCollege of ChemistryChemical Engineering and Materials ScienceSoochow UniversitySuzhou215123China State Key Laboratory of Radiation Medicine and Protection School for Radiological and Interdisciplinary Sciences(RAD-X)and Collaborative Innovation Center of Radiation Medicine of JiangsuSoochow UniversitySuzhou215123China

Temperature-responsive polymers have garnered significant attention due to their ability to respond to external *** this work,dual temperature-responsive block copolymers are synthesized via reversible addition-fragmentation chain transfer polymerization(RAFT)polymerization utilizing zwitterionic monomer methacryloyl ethyl sulfobetaine(SBMA) and N-isopropyl acrylamide(NIPAAm) as *** thermal responsive behaviors can be easily modulated by incorporating additional hydrophobic monomer benzyl acrylate(BN) or hydrophilic monomer acrylic acid(AA),adjusting concentration or pH,or varying the degree of polymerization of the block chain *** cloud points of the copolymers are determined by UV-Vis spectrophotometry,and these copolymers exhibit both controlled upper and lower critical solu bility temperatures(LCST and UCST) in aqueous *** study analyzes and summarizes the influencing factors of dual temperature responsive block copolymers by exploring the effects of various conditions on the phase transition temperature of temperature-sensitive polymers to explore the relationship between their properties and environment and structure to make them more selective in terms of temperature application range and regulation *** is very interesting that the introduction of poly-acrylic acid(PAA) segments in the middle of di-block copolymer PSBMA_(55)-b-PNIPAAm_(80) to form PSBMA_(55)-b-PAA_(x)-b-PNIPAAm_(80) results in a reversal of temperature-responsive behaviors from 'U'(LCST UCST) type,while the copolymer PSBMA_(55)-b-P(NIPAAm_(80)-co-AA_(x)) *** work provides a clue for tuning the phase transition behavior of polymers for manufacture of extreme smart materials.

关键词： Temperature responsive polymers High critical solubility temperature(UCST) Low critical solubility temperature(LCST) Block copolymers

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Health outcomes of electronic cigarettes

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中华医学杂志(英文版) 2024年第16期137卷 1903-1911页

作者： li Xinmeng Yuan lingzhi Wang fen Department of Gastroenterology The Third Xiangya Hospital Central South University Changsha Hunan China Hunan Key Laboratory of Non-resolving Inflammation and Cancer The Third Xiangya Hospital Central South University Changsha Hunan China

The usage of electronic cigarettes (e-cigarettes) sparked an outbreak of unidentified vaping-related lung disease in the US during late 2019. With e-cigarettes becoming more and more popular, smokers have more options other than conventional cigarettes. Under these circumstances, a comprehensive evaluation of the general safety of new tobacco and tobacco-related products, represented by e-cigarettes, to human health is necessary. In this review, we summarize the current research on potential negative impacts of e-cigarette exposure on human health. In particular, studies detailing the relationship between e-cigarettes and the digestive system are summarized, with mechanisms mainly including hepatic metabolic dysfunction, impaired gut barrier, and worsened outcomes of inflammatory bowel disease (IBD). Although believed to be safer than traditional cigarettes, e-cigarettes exert adverse effects on systemic health and induce the development of multiple diseases including asthma, cardiovascular disease, and IBD. Moreover, nicotine-containing e-cigarettes have a negative impact on the childhood development and increase the risk of arterial stiffness compared to the non-nicotine e-cigarettes. However, non-nicotine e-cigarette components have detrimental effects including promoting liver damage and metabolic disorders.

关键词： Electronic cigarettes Electronic nicotine delivery system Smoking cessation Health promotion Tobacco harm reduction Smoker

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Navigating interdisciplinary research:Historical progression and contemporary challenges

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Journal of Data and Information Science 2024年第3期9卷 14-28页

作者： Xiaoqiang li fen Cai Jintao Bao Yuqing jian Zehui Sun Xin Xie The Office of Science and Technology Development Peking UniversityBeijing 100871China National Center for Health Professions Education Development Peking UniversityBeijing 100871China Graduate School of Education Peking UniversityBeijing 100871China The Office of Scientific Research Peking UniversityBeijing 100871China

Interdisciplinary research plays a crucial role in addressing complex problems by integrating knowledge from multiple *** integration fosters innovative solutions and enhances understanding across various *** study explores the historical and sociological development of interdisciplinary research and maps its evolution through three distinct phases:pre-disciplinary,disciplinary,and *** identifies key internal dynamics,such as disciplinary diversification,reorganization,and innovation,as primary drivers of this ***,this study highlights how external factors,particularly the urgency of World War II and the subsequent political and economic changes,have accelerated its *** rise of interdisciplinary research has significantly reshaped traditional educational paradigms,promoting its integration across different educational ***,the inherent contradictions within interdisciplinary research present cognitive,emotional,and institutional challenges for ***,finding a balance between the breadth and depth of knowledge remains a critical challenge in interdisciplinary education.

关键词： Interdisciplinary research Historical sociology Development phases Interdisciplinary challenges

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Development in oxide metallurgy for improving the weldability of high -strength low-alloy steel-Combined deoxidizers and microalloying elements

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1263-1284页

作者： Tingting li jian Yang State Key Laboratory of Advanced Special Steel School of Materials Science and EngineeringShanghai UniversityShanghai 200444China

The mechanisms of oxide metallurgy include inducing the formation of intragranular acicular ferrite(IAF)using micron-sized inclusions and restricting the growth of prior austenite grains(PAGs)by nanosized particles during *** chaotically oriented IAF and refined PAGs inhibit crack initiation and propagation in the steel,resulting in high impact *** work summarizes the com-bined effect of deoxidizers and alloying elements,with the aim to provide a new perspective for the research and practice related to im-proving the impact toughness of the heat affected zone(HAZ)during the high heat input *** complex deoxidation with other strong deoxidants,such as Mg,Ca,Zr,and rare earth metals(REMs),can improve the toughness of the heat-affected zone(HAZ)by re-fining PAGs or increasing IAF ***,it is difficult to identify the specific phase responsible for IAF nucleation because ef-fective inclusions formed by complex deoxidation are usually *** alloying elements,such as C,Si,Al,Nb,or Cr,con-tents can impair HAZ toughness.A high C content typically increases the number of coarse carbides and decreases the potency of IAF ***,Cr,or Al addition leads to the formation of undesirable *** reduces the high-temperature stability of the ***,V,and B can enhance HAZ ***-containing precipitates present good thermal *** or V(C,N)is ef-fective in promoting IAF nucleation due to its good coherent crystallographic relationship with *** formation of the B-depleted zone around the inclusion promotes IAF *** interactions between alloying elements are complex,and the effect of adding dif-ferent alloying elements remains to be *** the future,the interactions between various alloying elements and their effects on ox-ide metallurgy,as well as the calculation of the nucleation effects of effective inclusions using first principles calculations will become the focus of

关键词： oxide metallurgy technology heat affected zone high-strength low-alloy steel intragranular acicular ferrite microalloying element

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Multidisciplinary comprehensive treatment of massive hepatocellular carcinoma with hemorrhage:A case report and review of literature

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World Journal of Gastrointestinal Oncology 2024年第5期16卷 2225-2232页

作者： Xian-Shuai Kou Fan-Fan li Yun Meng jian-Ming Zhao Sheng-fen liu Lan Zhang The First Clinical Medical College Gansu University of Chinese MedicineLanzhou 730000Gansu ProvinceChina Department of Thoracic Surgery The First Hospital of Lanzhou UniversityLanzhou 730000Gansu ProvinceChina Department of Surgery Gansu Provincial HospitalLanzhou 730000Gansu ProvinceChina Department of Orthopedics Gansu Provincial HospitalLanzhou 730000Gansu ProvinceChina

BACKGROUND Hepatocellular carcinoma(HCC),a major contributor to cancer-related deaths,is particularly prevalent in Asia,largely due to hepatitis B virus *** prognosis is generally *** case report contributes to the medical literature by detailing a unique approach in treating a large HCC through multidisciplinary collaboration,particularly in patients with massive HCC complicated by ruptured bleeding,a scenario not extensively documented *** SUMMARY The patient presented with large HCC complicated by intratumoral *** involved a multidisciplinary approach,providing individualized *** strategy included drug-eluting bead transarterial chemoembolization,sorafenib-targeted therapy,laparoscopic partial hepatectomy,and standardized sintilimab monoclonal antibody *** months after treatment,the patient achieved complete radiological remission,with significant symptom *** studies showed no lesions or recurrence,and clinical assessments confirmed complete *** report is notable as possibly the first docu-mented case of successfully treating such complex HCC conditions through integrated multidisciplinary efforts,offering new insights and a reference for future similar *** This study demonstrated effective multidisciplinary treatment for massive HCC with intratumoral bleeding,providing insights for future similar cases.

关键词： Hepatocellular carcinoma Transarterial chemoembolization Sintilimab Sorafenib Translational therapy Multidisciplinary team Case report

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Palladium-catalyzed multi components oxy-aminofluorination and aminofluorination of gem-difluoroalkenes

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Chinese Chemical Letters 2024年第2期35卷 420-425页

作者： fen Wu Xin li Junbiao Chang Dachang Bai State Key Laboratory of Antiviral Drugs NMPA Key Laboratory for Research and Evaluation of Innovative DrugKey Laboratory of Green Chemical Media and ReactionsMinistry of EducationSchool of Chemistry and Chemical EngineeringPingyuan LaboratoryHenan Normal UniversityXinxiang 453007China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

Organofluorine compounds are widely used in the realm of drug discovery and material ***,we developed palladium catalyzed intermolecular aminofluorination and oxy-aminofluorination of gem‑difluoroalkenes with N-fluorobenzenesulfonimide(NFSI),in which NFSI was used as the nitrogen source and *** reaction provides an efficient and straightforward synthesis route of a series ofα-trifluoromethyl benzylic ***,three/four components oxy-aminofluorination processes were realized to giveα-trifluoromethyl benzylic ether with a terminal amino group,which proceed through C(sp^(3))-O bond cleavage of easily available ether and simultaneous introduced a fluorine,an amino and an oxy substituent in one pot with excellent *** divergent reactivity not only included the incorporation of one ether molecular,but also much more challenged two ether insertion with excellent selectivity through succession C(sp^(3))-O bonds *** protocol allows for concise synthesis of high value amines with fluoroalkyl-substituents and selectively transformation of easily available ethers by high-valent palladium catalysis.

关键词： Palladium Multi components Aminofluorination Oxy-aminofluorination C(sp^(3))-O bond cleavage

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