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Acta Mechanica Sinica 2016年第4期32卷 731-742页

作者： W.Sun y.Liu School of Mechanical Engineering and Automation Northeastern University State Key Laboratory of Mechanical System and Vibration Institute of Vibration Shock and Noise Shanghai Jiao Tong University

The strain dependent characteristics of hard coatings make the vibration analysis of hard-coated composite structure become a challenging task. In this study, the modeling and the analysis method of a hard-coated composite beam was developed considering the strain dependent characteristics of coating material. Firstly, based on analyzing the properties of hard-coating material, a high order polynomial was adopted to characterize the strain dependent characteristics of coating materials. Then, the analytical model of a hard-coated composite beam was created by the energy method. Next, using the numerical method to solve the vibration response and the resonance frequencies of the composite beam, a specific calculation flow was also proposed. Finally,a cantilever beam coated with Mg O ＋ Al2_O_3 hard coating was chosen as the study case; under different excitation levels, the resonance region responses and the resonance frequencies of the composite beam were calculated using the proposed method. The calculation results were compared with the experiment and the linear calculation, and the correctness of the created model was verified. The study shows that compared with the general linear calculation, the proposed method can still maintain an acceptable precision when the excitation level is larger.

关键词： coated excitation modulus verified challenging characterize created considering acceptable polynomial

Joint utility optimization algorithm for secure hybrid spectrum sharing

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high Technology Letters 2022年第4期28卷 373-383页

作者： WANG yi hUANG rong XU yaohua JIANG Fang BAI Na TANG Tao hU yanjun Key Laboratory of Intelligent Computing&Signal Processing Ministry of EducationAnhui UniversityHefei 230601P.R.China

As the rapid development of wireless communication networks has resulted in better user experiences,the spectrum resources occupied and energy consumption have increased considerably and resulted in great *** address the energy consumption and cost problems of spectrum sharing in cognitive radio networks,a hybrid spectrum sharing model combining the free spectrum of authorized users and the leased spectrum of mobile network operators is *** on the hybrid model,a function of throughput and costs,including energy consumption and transaction costs,is constructed,and a joint utility optimization problem is *** transactions between secondary users and primary users are performed on the consortium blockchain on which users can directly trade spectrum and the transaction information is *** order to improve the joint utility,the Lagrange multiplier method is used to achieve the optimal solution for the sensing time,the number of secondary users involved in sensing,and the transmission *** simulation results show that the joint utility optimization algorithm proposed in this paper can achieve higher joint utility under the constraints of the minimum throughput requirement and maximum transmission power.

关键词： spectrum sharing power control joint utility blockchain

DEVELOPMENT OF ThE RISK-BASED MAINTENANCE OPTIMIZATION SySTEM FOR FOSSIL POWER PLANTS

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 381-386页

作者： D.Watanabe y.Chuman N.Nishimura h.Matsumoto K.Tominaga F.Sakata T.Kuroishi Nagasaki R&D Center Mitsubishi Heavy Industries Ltd. Fukahori-Machi Nagasaki 851-0392 Japan Nagasaki Shipyard & Machinery Works Mitsubishi Heavy Industries Ltd. Akunoura-Machi Nagasaki 850-8610 Japan Power Systems headquarters Mitsubishi Heavy Industries Ltd. Minato-Ku Tokyo 108-8215 Japan

Cost reduction in electric power generation is a major management concern, and it is therefore necessary to reduce maintenance expenses while upholding plant reliability. A maintenance optimization system 'FREEDOM', which uses RBM technique, DCF (discounted cash flow) and NPV (net present value) calculation functions, has been newly developed. This system probabilistically evaluates the lifetime of boiler and turbine and quantitatively calculates the risk defined as the cumulative probability of failure multiplied by the consequence of failure. Economically optimized timing of inspection and alternative countermeasure such as repair and replacement are then recommended. This system has already been applied to seven plants in Japan, and its effectiveness has been confirmed.

关键词： plant asset management risk based maintenance probabilistic life assessment maintenance optimization

Photocurrent Studies of Ultraviolet Detector Based on Gallium Nitride Epilayer

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Chinese Physics Letters 1996年第11期13卷 874-877页

作者： yANG Kai QIN Lin-hong ZhANG rong ShEN Bo ZhENG you-dou hUANG Zhen-chun JCChen Department of Physics Nanjing UniversityNanjing 210093 Department of Electrical Engineering University of Maryland Baltimore CountyBaltimoreMD 21228-5398USA

The properties of photoconductive blue and ultraviolet detector based on single crystal GaN epilayer grown on sapphire substrate by metalorganic chemical vapor deposition were *** observed optical absorption edge of 3.39eV in optical transmission has been confirmed by the peak of 3.400eV in *** detectable energy span of the GaN device up to ultraviolet was obtained by photocurrent *** dependence of the intensity of photocurrent on the chopper frequency in the measurement was studied,and an easy method was used to determine the response time as 0.4s.

关键词： measurement sapphire optical

Near Earth Vortices Driving of Field Aligned Currents Based on Magnetosphere Multiscale and Swarm Observations

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空间科学学报 2019年第1期39卷 9-17页

作者： ZhANG C ShEN C yANG y y DUNLOP M W TI S RUSSELL C T LühR h BURCh J L LINDQVIST P A TORBERT R B FRIIS-ChRISTENSEN E State Key Laboratory of Space Weather National Space Science Center College of Earth Science University of Chinese Academy of Sciences College of Science Harbin Institute of Technology Institute of China Seismological Bureau Crustal Stress Space Science Institute School of Astronautics Beihang University Rutherford Appleton Laboratory University of California German Research Center For Geosciences German Research Center for Geosciences Southwest Research Institute Royal Institute of Technology University of New hampshire Danish National Space Center

A long-standing mystery in the study of Field-Aligned Currents(FACs) has been that: how the currents are generated and why they appear to be much stronger at high altitudes than in the ionosphere. here we present two events of magnetotail FACs observed by the Magnetospheric Multiscale Spacecraft(MMS) on 1 st July and 14 th July 2016, to show how the Substorm Current Wedges(SCW) were formed. The results show that particles were transferred heading towards the Earth during the expansion phase of *** azimuthal flow formed clockwise(counter-clockwise) vortex-like motion, and then generated downward(upward) FACs on the tailward/poleward side of the distorted field with opposite vorticity on their Earthward/equatorward side. We also analyzed the Region 1 FACs observed by the Earth Explorer Swarm spacecraft on 1 st July 2016 and found that they were associated with FACs observed by MMS, although differing by a factor of 10. This difference suggests that either there was the closure of the currents at altitudes above 500 km or the currents were not strictly parallel to B and closed at longitudes away from where they were generated.

关键词： Substorm current wedge Magnetosphere Field-aligned currents Flow vorticity Multiple spacecraft measurements

Formation of spheroidal microstructure in semi-solid state and thixoforming of 7075 high strength aluminum alloy

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Rare Metals 2015年第10期34卷 710-716页

作者： Chang-Peng Wang Ze-Jun Tang hua-Sheng Mei Ling Wang rong-Qiang Li Di-Fan Li Environmental Testing Center No. 59 Institute of China Ordnance Industry Corrosion and Protection Center University of Science and Technology Beijing Mechanical and Electrical College Nanjing University of Aeronautics & Astronautics

The effects of isothermal holding process on the microstructure evolution of semi-solid 7075 strength aluminum alloy produced by the recrystallisation and partial remelting(RAP) process were investigated. Tensile mechanical properties of as-received and thixoformed alloys at room temperature were examined. The results show that the microstructure of as-received alloy exhibits remarkable orientation along the deformation *** the increase of isothermal holding time, the solid particle grain size continuously increases and the degree of spheroidization also improves. Coalescence mechanism is dominant when reheated at 595 °C and Ostwald ripening mechanism is dominant when reheated at 615 °C in the semi-solid state. A lower coarsening rate is observed for 615 °C(coarsening rate K = 391 μm3 s-1) compared with the coarsening rate for 595 °C(coarsening rate K = 501 μm3 s-1). The RAP 7075 aluminum alloy can be successfully thixoformed and the filling of components is good after thixoforming. The thixoformed components exhibit favorite mechanical properties.

关键词： 7075 high strength aluminum alloy Spheroidal micro

NUMERICAL SIMULATION OF COLUMNAR TO EQUIAXED TRANSITION FOR DIRECTIONALLy SOLIDIFIED Ti-44Al ALLOy

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Acta Metallurgica Sinica(English Letters) 2008年第2期21卷 146-156页

作者： K.F. Wang J.J. Guo G.F. Mi C. y. Li h.Z. Fu School of IVlaterials Science and Engineering Henan Polytechnic University Jiaozuo 454100 China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

Solute diffusion controlled solidification model was applied to simulate the columnar to equiaxed transition （CET） during directional solidification of Ti-44Al alloy. The simulation results show that the solutal interactions from growing equiaxed grains play an important role on CET. The effects of the applied thermal gradient and pulling velocity, the equiaxed seed spacing and nucleation undercooling on the CET are investigated in the present simulation. The simulated results indicated that the columnar branch spacing depends not only on the thermal gradient and the pulling velocity, but also on number of the seeds. A spacing adjustment can occur through initiation of seeds that develop into new columnar grains. The dependence of the CET on the thermal gradient and pulling velocity, qualitatively agrees with the analytical CET model of hunt,

关键词： Ti-44Al alloy Directional solidification columnar to equiaxedtransition (CET) Numerical simulation

ChANGES OF PAN EVAPORATION IN ThE UPPER REACh OF ThE yANGTZE RIVER

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Journal of hydrodynamics 2011年第4期23卷 503-509页

作者： rong yan-shu WANG Wen JIANG hai-yan College of hydrology and Water Resources Hohai University Nanjing 210098 China State Key Laboratory of hydrology-Water Resources and hydraulic Engineering Hohai University Nanjing 210098 China

The upper reach of the yangtze River, 4 511 km long from west to east, contains a great amount of water resources of the yangtze River Basin. This article studies the characteristics of the pan evaporation, the related meteorological variables, and their effects on the pan evaporation, based on the data of the daily pan evaporation （1980-2008） and other meteorological variables （1961-2008）. The results show that the linear trend of the pan evaporation has remarkable regional features, i.e., the decrease trend in the southwest and the increase trend in the northeast of the investigated region, and the yangtze River is approximately the boundary of these trends. The meteorological variables have different effects on the pan evaporation depending on the fact that they are in the category the thermal variables or the dynamic variables. The thermal meteorological variables （i.e., air temperature, diurnal temperature range, and sunshine duration） have positive partial correlations with the pan evaporation, while the dynamic ones （air pressure, rainfall, and relateive humidity） have negative correlations with the pan evaporation. The correlation of the wind speed remains to be investigated.

关键词： linear time trend meteorological variable pan evaporation partial correlation yangtze River

history of helicobacter pylori,duodenal ulcer,gastric ulcer and gastric cancer

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World Journal of Gastroenterology 2014年第18期20卷 5191-5204页

作者： David y Graham Michael E DeBakey VA Medical Center Baylor College of MedicineHoustonTX 77030United States

helicobacter pylori (h. pylori) infection underlies gastric ulcer disease, gastric cancer and duodenal ulcer disease. The disease expression reflects the pattern and extent of gastritis/gastric atrophy (i.e., duodenal ulcer with non-atrophic and gastric ulcer and gastric cancer with atrophic gastritis). Gastric and duodenal ulcers and gastric cancer have been known for thousands of years. Ulcers are generally non-fatal and until the 20th century were difficult to diagnose. however, the presence and pattern of gastritis in past civilizations can be deduced based on the diseases present. It has been suggested that gastric ulcer and duodenal ulcer both arose or became more frequent in Europe in the 19th century. here, we show that gastric cancer and gastric ulcer were present throughout the 17th to 19th centuries consistent with atrophic gastritis being the predominant pattern, as it proved to be when it could be examined directly in the late 19th century. The environment before the 20th century favored acquisition of h. pylori infection and atrophic gastritis (e.g., poor sanitation and standards of living, seasonal diets poor in fresh fruits and vegetables, especially in winter, vitamin deficiencies, and frequent febrile infections in childhood). The latter part of the 19th century saw improvements in standards of living, sanitation, and diets with a corresponding decrease in rate of development of atrophic gastritis allowing duodenal ulcers to become more prominent. In the early 20th century physician’s believed they could diagnose ulcers clinically and that the diagnosis required hospitalization for “surgical disease” or for “Sippy” diets. We show that while h. pylori remained common and virulent in Europe and the United States, environmental changes resulted in changes of the pattern of gastritis producing a change in the manifestations of

关键词： helicobacter pylori Duodenal ulcer Gastric ulcer Gastric cancer Medical history Ulcer surgery Epidemiology Gastritis Atrophic gastritis Antiquity

Deriving Ag_3PO_4–CaO composite as a stable and solar light photocatalyst for efficient ammonia degradation from wastewater

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Journal of Energy Chemistry 2018年第1期27卷 290-299页

作者： y.Shaveisi S.Sharifnia Catalyst Research Center Chem.Eng.Dept.Razi UniversityKermanshah 67149-67246lran

A novel Ag3PO4-CaO composite photocatalyst with enhanced photocatalytic activity was synthesized and utilized for degradation of ammonia from aqueous solution under sunlight. Ag3PO4 was prepared by pre- cipitation method, and the composite of AgjPO4-CaO was prepared via impregnation method. Utilization of eggshell for CaO synthesis provided a cost-effective and environmental friendly way for the hetero- geneous catalyst production. The as-prepared photocatalysts were characterized by FT-IR, FE-SEM, TEM, EDX, UV-vis and PL Results show that the Ag3PO4-CaO samples have excellent photocatalytic perfor- mances in the wide visible-light region. The effect of operating parameters like the content of Ag3PO4 in composite, initial ammonia concentration, ph of solution, catalyst dosage and oxygen supply was investi- gated. The photoeatalyst with 60 wt% content of Ag3PO4 had a high photocatalytic performance, because a low content of Ag3PO4 causes weak light absorption, and the excess amount of it results in serious electron-hole recombination due to the aggregation of AgjPO4 particles. The maximum ammonia degra- dation （about 70%） was achieved in 340 mg/L of ammonia, ph 11, and 1.25 g/L of catalyst in the presence of pure oxygen. In comparison to Ag3PO4, 60 wt% AgjPO4-CaO had a good stability and it could have been easily separated from the solution for recycling.

关键词： Photocatalyst Ag3PO4 CaO Ammonia degradation Sunlight