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Nonlinear analysis on dynamic buckling of eccentrically stiffened functionally graded material toroidal shell segment surrounded by elastic foundations in thermal environment and under time-dependent torsional loads

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Applied mathematics and mechanics(English Edition) 2016年第7期37卷 835-860页

作者： D.V.DUNG p.m.VUONG Department of mathematics Mechanics and InformaticsVietnam National University Faculty of Civil and Industrial National University of Civil Engineering

The nonlinear analysis with an analytical approach on dynamic torsional buckling of stiffened functionally graded thin toroidal shell segments is investigated. The shell is reinforced by inside stiffeners and surrounded by elastic foundations in a thermal environment and under a time-dependent torsional load. The governing equations are derived based on the Donnell shell theory with the yon Karman geometrical nonlinearity, the Stein and mcElman assumption, the smeared stiffeners technique, and the Galerkin method. A deflection function with three terms is chosen. The thermal parameters of the uniform temperature rise and nonlinear temperature conduction law are found in an explicit form. A closed-form expression for determining the static critical torsional load is obtained. A critical dynamic torsional load is found by the fourth-order Runge-Kutta method and the Budiansky-Roth criterion. The effects of stiffeners, foundations, material, and dimensional parameters on dynamic responses of shells are considered.

关键词： toroidal shell segment functionally graded material (FGm) stiffened shell,critical static and dynamic torsional load thermal environment

Nanotexturing and Wettability Ageing of polypropylene Surfaces modified by Oxygen Capacitively Coupled Radio Frequency plasma

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Journal of materials Science & Technology 2014年第10期30卷 965-972页

作者： Y.p.Li m.K.Lei Surface Engineering Laboratory School of Materials Science and EngineeringDalian University of Technology

polypropylene （pp） was treated by an oxygen capacitively coupled radio frequency plasma （CCp） under a radio frequency （RF） power of 200 W for exposure time of 1, 5, and 10 rain. The ageing process of the plasma- treated pp was studied at an ageing temperature of 90 ~C during an ageing time up to 25 h. The formation of the nanotextures with different geometry and aspect ratio and the grafting of large number of oxygen- containing groups were achieved on as-treated pp surfaces under the oxygen CCp treatment for the increased exposure time. The hydrophilicity on the as-treated pp surfaces with the stable nanotextures was rapidly depressed during the ageing process at 90 ℃ due to the restructuring of chemical composition. The surface restructuring rate was dependent on the aspect ratio and the oxygen-containing groups on the nanotextured pp with increasing exposure time. The hydrophobic over-recovery to high hydrophobicity and superhydrophobicity were observed on the post-aged surfaces with the stable nanofibrils from as-treated hydrophilic surfaces. The superhydrophobicity with the low water adhesion was achieved on the post-aged surfaces preserving the nanofibrils with high aspect ratio and large distance due to the decrease of the oxygen-containing groups after the surface restructuring.

关键词： polypropylene plasma nanotexturing Ageing Surface restructuring Superhydrophobicity

Robust Control Strategy for Inductive parametric Uncertainties of DC/DC Converters in Islanded DC microgrid

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Journal of modern power Systems and Clean Energy 2023年第1期11卷 335-344页

作者： Salisu Abdullahi Tao Jin p.m.Lingom School of Electrical Engineering and Automation Fuzhou UniversityFuzhouChina

Direct current(DC) microgrid consists of many parallel power converters that share load currents through the inductance of DC/DC converters. Usually, the inductance parameters are dependent on the physical implementation of the system, and their values may not match their nam.plates. Such disparities could lead to unequal response characteristics of the system, which can potentially reduce the performances of the DC microgrid operation. This paper proposes a robust control strategy for inductive parametric uncertainties of DC/DC converters using an optimal control method with integral action. To achieve such a goal, the system model parameters with nominal values are transformed into parametric unmatched uncertainties to form a robust control problem, which is then transformed into a linear quadratic regulator problem. The inductance uncertainties are stabilized with the uncertainty dynamic algebraic Riccati equation(UDARE) using state feedback gain under linear quadratic regulator. The closed-loop control with integral action is adopted to achieve a steady-state error of zero on the DC-link voltage at any uncertainty of the inductive parameter, which subsequently ensures the equal load current sharing. Off-line simulations and real-time validations based on OpalRT have been conducted to demonstrate the effectiveness and robustness of the proposed robust control strategy.

关键词： DC/DC converter DC microgrid OpalRT optimal control parametric uncertainty robust control

Integral treatment for forced convection heat and mass transfer of nanofluids over linear stretching sheet

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Applied mathematics and mechanics(English Edition) 2015年第3期36卷 337-352页

作者： A.NOGHREHABADI p.SALAmAT m.GHALAmBAZ Department of mechanical Engineering Shahid Chamran University of Ahvaz

An integral treatment is proposed for the analysis of the forced convection flow of a nanofluid over a stretching sheet. The obtained results agree well with the numerical results. The results of the presented solution provide an analytic solution, which can be conveniently used in engineering applications. Four types of nanoparticles, i.e., alumina （Al2O3）, silicon dioxide （Si02）, silver （Ag）, and copper （Cu）, dispersed in the base fluid of water are examined. The analytical results show that an increase in the volume fraction of nanoparticles increases the thickness of the thermal boundary layer. The reduced Nusselt number is a decreasing function of the volume fraction of nanoparticles. ＇ Key words nanofluid, integral method, stretching sheet, analytical solution, thermal enhancement

关键词： nanofluid integral method stretching sheet analytical solution thermal enhancement

Deeply concealed half-graben at the SW margin of the East European Craton(SE poland)-Evidence for Neoproterozoic rifting prior to the break-up of Rodinia

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Journal of palaeogeography 2018年第1期7卷 88-97页

作者： p.Krzywiec p.poprawa m.mikotajczak S.mazur m.malinowski Institute of Geological Sciences Polish Academy of SciencesWarsawPoland AGH University of Sciences and Technology CracowPoland Institute of Geophysics Polish Academy of SciencesWarsawPoland

Baltica was one of continents formed as a result of Rodinia break-up 850-550 ma. It was separated from Amazonia(?) by the Tornquist Ocean, the opening of which was preceded by Neoproterozoic extension in a network of continental rifts. Some of these rifts were subsequently aborted whereas the Tornquist Rift gave rise to splitting of Rodinia and formation of the Tornquist Ocean. The results of 1-D subsidence analysis at the fossil passive margin of Baltica provided insight in the timing and kinematics of continental rifting that led to break-up of Rodinia. Rifting was associated with Neoproterozoic syn-rift subsidence accompanied by deposition of continental coarse-grained sediments and emplacement of continental *** from a syn-rift to post-rift phase in the latest Ediacaran to earliest early Cambrian was concomitant with deposition of continental conglomerates and arkoses, laterally passing into mudstones. An extensional scenario of the break-up of Rodinia along the Tornquist Rift is based on the character of tectonic subsidence curves, evolution of syn-rift and post-rift depocenters in time, as well as geochemistry and geochronology of the syn-rift volcanics. It is additionally reinforced by the high-quality deep seismic reflection data from SE poland, located above the SW edge of the East European Craton. The seismic data allowed for identification of a deeply buried(11-18 km), well-preserved extensional half-graben, developed in the palaeoproterozoic crystalline basement and filled with a Neoproterozoic syn-rift volcano-sedimentary succession. The results of depth-to-basement study based on integration of seismic and gravity data show the distribution of local NE-SW elongated Neoproterozoic depocenters within the SW slope of the East European Craton. Furthermore,they document the rapid south-eastwards thickness increase of the Neoproterozoic succession towards the NW-SE oriented craton margin. This provides evidence for extensive crustal thinning o

关键词： Rodinia Baltica Tornquist rift Orsha-Volyn Aulacogen Tornquist Ocean Neoproterozoic Seismic data Gravity data

mosquito larvicidal and ovicidal properties of Eclipta alba(L.) Hassk(Asteraceae) against chikungunya vector,Aedes aegypti(Linn.)(Diptera:Culicidae)

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Asian pacific Journal of Tropical medicine 2011年第1期4卷 24-28页

作者： m Govindarajan p Karuppannan Division of phytochemistry and Vector Biology Department of ZoologyAnnamalai UniversityAnnamalai Nagar-608 002India

Objective:The present study deals with the investigation of larvicidal and ovicidal activities of benzene,hexane,ethyl acetate,methanol and chloroform leaf extract of Eclipta alba（***） against dengue vector,Aedes aegypti（***）.methods:Twenty five earlyⅢinstar larvae of *** was exposed to various concentrations（50-300 ppm） and was assayed in the laboratory by using the protocol of WHO 2005;the 24 h LC50 values of the *** leaf extract was determined by probit *** ovicidal activity,slightly modified method of Su and mulla was *** ovicidal activity was determined against *** to various concentrations ranging from 100-350 ppm under the laboratory *** egg hatch rates were assessed 48 h post ***:The LC50 values of benzene,hexane,ethyl acetate,methanol and chloroform extract of *** against early third instar larvae of *** were 151.38,165.10, 154.88,127.64 and 146.28 ppm,*** larvicidal activity was observed in the methanol extract followed by chloroform,benzene,ethyl acetate and hexane *** mortality was observed in *** five solvent tested the methanol extract was found to be most effective for ovicidal activity against *** methanol extracts exerted 100%mortality （zero hatchability） at 300 ***:From the results it can be concluded the crude extract of *** was an excellent potential for controlling *** mosquito.

关键词： Eclipta alba Aedes aegypti Larvicidal activity Ovicidal activity

multi-objective Optimization of Continuous Drive Friction Welding process parameters Using Response Surface methodology with Intelligent Optimization Algorithm

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Journal of Iron and Steel Research International 2015年第10期22卷 954-960页

作者： p.m.AJITH T.m.AFSAL HUSAIN p.SATHIYA S.ARAVINDAN Department of production Engineering National Institute of Technology Department of mechanical Engineering Indian Institute of Technology Delhi

The optimum friction welding （FW） parameters of duplex stainless steel （DSS） UNS $32205 joint was determined. The experiment was carried out as the central composite array of 30 experiments. The selected input parameters were friction pressure （F）, upset pressure （U）, speed （S） and burn-off length （B）, and responses were hardness and ultimate tensile strength. To achieve the quality of the welded joint, the ultimate tensile strength and hardness were maximized, and response surface methodology （RSm） was applied to create separate regression equations of tensile strength and hardness. Intelligent optimization technique such as genetic algorithm was used to predict the pareto optimal solutions. Depending upon the application, preferred suitable welding parameters were selected. It was inferred that the changing hardness and tensile strength of the friction welded joint influenced the upset pressure, friction pressure and speed of rotation.

关键词： friction welding response surface methodology genetic algorithm pareto front multi-objective optimization duplex stainless steel

Evaluation and prediction of blast induced ground vibration using support vector machine

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mining Science and Technology 2010年第1期20卷 64-70页

作者： KHANDELWAL m KANKAR p K HARSHA S p Department of mining Engineering College of Technology & Engineering Maharana Pratap University of Agriculture & Technology Udaipur 313001 India Department of mechanical & Industrial Engineering Indian Institute of Technology Roorkee 247667 India

We present the application of Support Vector machine (SVm) for the prediction of blast induced ground vibration by taking into consideration of maximum charge per delay and distance between blast face to monitoring point. To investigate the suitability of this approach, the predictions by SVm have been compared with conventional predictor equations. Blast vibration study was carried out at magnesite mine of pithoragarh, India. Total 170 blast vibrations data sets were recorded at different strate-gic and vulnerable locations in and around to mine. Out of 170 data sets, 150 were used for the training of the SVm network as well as to determine site constants of different conventional predictor equations, whereas, 20 new randomly selected data sets were used to compare the prediction capability of SVm network with conventional predictor equations. Results were compared based on Co-efficient of Determination (CoD) and mean Absolute Error (mAE) between monitored and predicted values of peak particle Veloc-ity (ppV). It was found that SVm gives closer values of predicted ppV as compared to conventional predictor equations. The coef-ficient of determination between measured and predicted ppV by SVm was 0.955, whereas it was 0.262, 0.163, 0.337 and 0.232 by USBm, Langefors-Kihlstrom, Ambraseys-Hendron and Bureau of Indian Standard equations, respectively. The mAE for ppV was 11.13 by SVm, whereas it was 0.973, 1.088, 0.939 and 1.292 by USBm, Langefors-Kihlstrom, Ambraseys-Hendron and Bureau of Indian Standard equations respectively.

关键词： blast vibration support vector machine generalised predictor equations

Behavior of argon gas release from manganese oxide minerals as revealed by ^(40)Ar/^(39)Ar laser incremental heating analysis

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Chinese Science Bulletin 2002年第18期47卷 1502-1510页

作者： p. m. Vasconcelos Faculty of Earth Resources China University of Geosciences Wuhan China Department of Earth Sciences The University of Queensland Brisbane Australia

manganese oxides in association with paleo-weathering may provide significant insights into the multiple factors affecting the formation and evolution of weathering profiles, such as temperature, precipitation, and biodiversity. Laser probe step-heating analysis of supergene hollandite and cryptomelane samples collected from central Queensland, Australia, yield well-defined plateaus and consistent isochron ages, confirming the feasibilityy dating very-fined supergene manganese oxides by 40Ar/39 Ar technique. Two distinct structural sites hosting Ar isotopes can be identified in light of their degassing behaviors obtained by incremental heating analyses. The first site, releasing its gas fraction at the laser power 0.2-0.4 W, yields primarily 40Aratm, 38Aratm, and 36Aratm(atmospheric Ar isotopes). The second sites yield predominantly 40Ar*(radiogenic 40Ar), 39Ark, and Ark (nucleogenic components), at -0.5-1.0 W. There is no significant Ar gas released at the laser power higher than 1.0 W, indicating the

关键词： hollandite cryptomelane 40Ar/39Ar laser incremental heating argon degassing tunnel site.