检索结果-南通市图书馆

Application of BeiDou navigation satellite system in emergency rescue of natural hazards: a case study for field geological survey of Qinghai−Tibet plateau

在线全文

学校读者我要写书评

暂无评论

Geo-Spatial Information Science 2018年第4期21卷 294-301页

作者： Ming Hao Jianlong Zhang Ruiqing niu Changrong Deng hong Liang National Engineering Research Center for Geographic Information System WuhanChina Chengdu Center of China Geological Survey ChengduChina

In recent years,geological and mineral resources exploration in China has expanded to deep hinterland of the Qinghai−Tibet Plateau and other regions with complex geological *** special natural conditions of Qinghai−Tibet Plateau determine the characteristics of“life-forbidden zone”that is characterized by alpine hypoxia,changeable weather,complex road conditions,and beast *** particular,the work in wild depopulated zones with severe environment and poor communications imposes serious threats to the life safety of geological ***,how to guarantee the safety of geological personnel working on the Qinghai−Tibet Plateau and how to reduce or even avoid casualty of geological personnel have currently become the urgent *** this study,an emergency rescue information system for field geological survey is constructed based on BeiDou Navigation Satellite System.A case study of emergency rescue has been conducted in the depopulated zone of the Qinghai−Tibet Plateau and good effects have been achieved,providing security assurance for personnel engaged in field geological survey on the Qinghai−Tibet Plateau and technical support for the emergency rescue in case of natural hazards on the Qinghai−Tibet *** BeiDou Navigation Satellite System(BDS)can be effectively used to locate and communicate in the emergency rescue for rigorous Geological survey task where there is no network signal for the mobile phone,and the emergency rescue guarantee system is independent,reliable,and relatively *** application value of BDS is demonstrated in the geological field.

关键词： BeiDou navigation satellite system(BDS) natural hazard emergency rescue Qinghai−Tibet plateau

On traceable iterated line graph and hamiltonian path index

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

Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 239-252页

作者： niu Zhao-hong XIONG Li-ming YANG Wei-hua School of Mathematical Sciences Shanxi UniversityTaiyuan 030006China School of Mathematics and Statistics Beijing Key Laboratory on MCAACIBeijing Institute of TechnologyBeijing 100081China Department of Mathematics Taiyuan University of TechnologyTaiyuan 030024China

Xiong and Liu[21]gave a characterization of the graphs G for which the n-iterated line graph L^(n)(G)is hamiltonian,for n≥*** this paper,we study the existence of a hamiltonian path in L^(n)(G),and give a characterization of G for which L^(n)(G)has a hamiltonian *** applications,we use this characterization to give several upper bounds on the hamiltonian path index of a graph.

关键词： iterated line graph traceable hamiltonian index hamiltonian path index

Lattice reduction aided belief propagation for massive MIMO detection

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2019年第4期62卷 127-139页

作者： Senjie ZHANG zhiqiang HE Kai niu Shi JIN hong CHENG Key Laboratory of Universal Wireless Communications Ministry of EducationBeijing University of Posts and Telecommunications National Mobile Communications Research Laboratory Southeast University Intel Labs China

Efficient massive MIMO detection for practical deployment, which is with spatially correlated channel and high-order modulation, is a challenging topic for the fifth generation mobile communication(5G). In this paper, lattice reduction aided belief propagation(LRA-BP) is proposed for massive MIMO detection. LRA-BP applies the message updating rules of Markov random field based belief propagation(MRF-BP) in lattice reduced MIMO system. With the lattice reduced, well-conditioned MIMO channel,LRA-BP obtains better message updating and detection performance in spatially correlated channel than MRF-BP. Log-domain arithmetic is used in LRA-BP for computational complexity reduction. Simulation result shows that LRA-BP outperforms MRF-BP with 3–10 dB in terms of required SNR for 1% packet error rate in spatially correlated channel for 256-QAM. We also show that LRA-BP requires much lower complexity compared with MRF-BP.

关键词： massive MIMO MIMO detection belief propagation graph-based detection lattice reduction Markov random field

Investigation of Vapor-liquid Ejector with Organic Working Fluids

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2019年第1期28卷 61-71页

作者： CHEN Jianyong HUANG Yisheng niu zhiting LUO Xianglong CHEN Ying YANG zhi School of Material and Energy Guangdong University of Technology Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter

The vapor-liquid ejector is a simply flow device and driven by thermal energy. In this paper, a modified mathematical model of the vapor-liquid ejector is proposed, and the validation shows good agreements with the experimental data. A study is carried out with six organic working fluids, namely R1233 zd(E), R1336 mzz(Z), R236 ea, R245 ca, R245 fa and R365 mfc. The influences of the entrainment ratio, the area ratio, the superheating at the vapor nozzle inlet, the subcooling at the liquid nozzle inlet, and the pressures at these inlets on the pressure lifting are parametrically investigated. An increase in the subcooling leads to the great increasing of pressure lifting and the superheating has slight effect on the pressure lifting, whereas others have the opposite tendency. The studies of the pressures and temperatures at the typical locations inside the vapor-liquid ejector are further conducted by using R1336 mzz(Z). The results show that the above parameters have great influence on these pressures and temperatures inside except that the pressures are insignificantly impacted by the superheating, and the temperatures are negligibly affected by the area ratio. R1336 mzz(Z) is recommended as a good working fluid for the vapor-liquid ejector.

关键词： vapor-liquid ejector modelling organic fluids pressure lifting

Improved tensile properties of Al_(0.5)CoCrFeNi high-entropy alloy by tailoring microstructures

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2021年第9期40卷 2508-2513页

作者： Si-Zhe niu hong-Chao Kou Jun Wang Jin-Shan Li State Key Laboratory of Solidiﬁcation Processing Northwestern Polytechnical UniversityXi’an 710072China

The effect of heat treatment on microstructure and tensile properties of as-cast Al_(0.5)CoCrFeNi high-entropy alloy was investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM) equipped with energy-dispersive spectroscopy(EDS), and tensile *** results show that heat treatment strongly affects the microstructure, particularly the morphology of bcc phases,and improves tensile properties. Microstructure analysis reveals that rod-shaped and elliptoid phases appear in the matrix after heat treatment at 1150 ℃. Besides, under850 ℃ heat-treated condition, ultimate tensile strength increases by about 60% without sacrificing much plasticity,which can be attributed to the content of bcc phases and fine precipitates dispersed in the dendrites. For other heattreated conditions, tensile ductility increases by at least30%, especially 60% for heat treatment at 450 ℃, and strength also improves. Fracture analysis indicates that the fracture mode of heat treatment at 850 ℃ is a mixture of quasi-cleavage and ductile fracture, while the other heattreated conditions show the mode of ductile fracture.

关键词： High-entropy alloys Heat treatment Microstructure Tensile properties

Study on heavy metal concentrations in river sediments through the total amount evaluation method

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第5期12卷 399-404页

作者： Chen-chen WANG zhi-guang niu Yan LI Jie SUN Fang WANG School of Environment Science and Technology Tianjin University Tianjin 300072 China Yangtze River Waterway Bureau Encamped in the Binhai Office Tianjin 300072 China Tianjin Urban Construction Design Institute Co. Ltd Tianjin 300072 China

A quantitative method to evaluate the amounts of heavy metals in river sediments is established. Using the BT Drainage River in North China as a study object, six representative cross sections were selected for measurement of heavy metal indicators in sediments, and then the main contamination indicators were determined by performing a potential ecological risk assessment. Using a section of this river as an example, the total amounts of the main pollution indicators and those of their harmful forms are estimated by the Surfer software, which simulates the pollution status within the downstream sediments of the outfall at this section. The calculation results could provide a theoretical guideline and data support for pollution treatment of the BT Drainage River.

关键词： Total amount evaluation Heavy metal pollution River sediments Surfer software

Latest developments in precancerous lesions of hepatocellular carcinoma

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2016年第12期22卷 3305-3314页

作者： Zhao-Shan niu Xiao-Jun niu Wen-hong Wang Jing Zhao Laboratory of Micromorphology Medical College of Qingdao University Clinical Medicine Specialty Medical College of Qingdao University Department of Pathology Medical College of Qingdao University Department of Pathology the Affiliated Hospital of Qingdao University

Hepatocarcinogenesis in human chronic liver diseases is a multi-step process in which hepatic precancerous lesions progress into early hepatocellular carcinoma(HCC) and progressed HCC, and the close surveillance and treatment of these lesions will help improve the survival rates of patients with HCC. The rapid development and extensive application of imaging technology have facilitated the discovery of nodular lesions of ambiguous significance, such as dysplastic nodules. Further investigations showed that these nodules may be hepatic precancerous lesions, and they often appear in patients with liver cirrhosis. Although the morphology of these nodules is not sufficient to support a diagnosis of malignant tumor, these nodules are closely correlated with the occurrence of HCC, as indicated by long-term follow-up studies. In recent years, the rapid development and wide application of pathology, molecular genetics and imaging technology have elucidated the characteristics of precancerous lesions. Based on our extensive review of the relevant literature, this article focuses on evidence indicating that high-grade dysplastic nodules are more likely to transform into HCC than low-grade dysplastic nodules based on clinical, pathological, molecular genetic and radiological assessments. In addition, evidence supporting the precancerous nature of large cell change in hepatitis B virus-related HCC is discussed.

关键词： Hepatocellular carcinoma Precancerous lesions High-grade dysplastic nodule Large cell change Small cell change

Morphologic changes of simple star dunes during the growth process in Dunhuang,China

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 Mountain Science 2022年第4期19卷 1095-1106页

作者： AN zhi-shan ZHANG Ke-cun TAN Li-hai niu Qing-he LIU Ben-li niu Bai-cheng Dunhuang Gobi and Desert Research Station Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Key Laboratory of Desert and Desertification Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China

Star dune is one typical kind of aeolian geomorphology in global sand *** has attracted scholars in various research fields for years because of its unique morphologic features like Egyptian *** landform pattern of star dune is mainly dominated by factors such as regional wind regime,sand availability,and local *** dunes grow vertically as they accumulate sand brought in from different directions;however,little is known regarding morphologic changes during this *** stability of star dunes based on quantitative data is another unsolved question due to the limitation in measuring equipment or other *** whether the star dune can grow into star sand hills is another scientific problem which needs to be *** this paper,the heightening development process and morphological changes of star dunes were monitored in Mingsha Mountain of Dunhuang with the 3D laser *** show that the star dunes in Mingsha Mountain were formed by a group of relatively steady winds,which were northwest,northeast and south *** the increase of the height of the star dunes,the morphological parameters of the dune,such as the volume and bottom area,did not show regular *** surface erosion of both Dune 1 and Dune 2 during the observation period was closely related to the regional wind *** the growth of the star dunes,the overall trend of the dunes was relatively steady and the dune shape maintained its stability although the aspect and slope of the sand dunes changed,indicating that the stability of star dune was not complete and was ***,the variation range of the dune slope was proportional to the volume change of the dune.

关键词： Star dune 3D laser scanner Dunhuang Morphologic change

UAV-assisted cooperative offloading energy efficiency system for mobile edge computing

在线全文

学校读者我要写书评

暂无评论

Digital Communications and Networks 2024年第1期10卷 16-24页

作者： Xue-Yong Yu Wen-Jin niu Ye Zhu hong-Bo Zhu Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Nanjing210003China Engineering Research Centerof Health Service System Based on Ubiquitous Wireless Networks Ministry of EducationNanjng Universityof Posts and Telecommunications Nanjing210003China

Reliable communication and intensive computing power cannot be provided effectively by temporary hot spots in disaster areas and complex terrain ground *** this has greatly developed the application and integration of UAV and Mobile Edge Computing(MEC)to the Internet of Things(loT).However,problems such as multi-user and huge data flow in large areas,which contradict the reality that a single UAV is constrained by limited computing power,still *** to allowing UAV collaboration to accomplish complex tasks,cooperative task offloading between multiple UAVs must meet the interdependence of tasks and realize parallel processing,which reduces the computing power consumption and endurance pressure of *** the computing requirements of the user terminal,delay constraint of a computing task,energy constraint,and safe distance of UAV,we constructed a UAV-Assisted cooperative offloading energy efficiency system for mobile edge computing to minimize user terminal energy ***,the resulting optimization problem is originally nonconvex and thus,difficult to solve *** tackle this problem,we developed an energy efficiency optimization algorithm using Block Coordinate Descent(BCD)that decomposes the problem into three convex ***,we jointly optimized the number of local computing tasks,number of computing offloaded tasks,trajectories of UAV,and offloading matching relationship between multi-UAVs and multiuser *** results show that the proposed approach is suitable for different channel conditions and significantly saves the user terminal energy consumption compared with other benchmark schemes.

关键词： Computation offloading Internet of things(IoT) Mobile edge computing(MEC) Block coordinate descent(BCD)