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performance enhancement of water bath heater at natural gas city gate station using twisted tubes

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Chinese Journal of Chemical Engineering 2020年第1期28卷 165-179页

作者： p.Soleimani M.Khoshvaght-Aliabadi h.Rashidi h.Bahmanpour Department of Chemical Engineering Shahrood BranchIslamic Azad UniversityShahroodIran Department of Environment Shahrood BranchIslamic Azad UniversityShahroodIran

Natural gas is transported from producing regions to consumption regions by using transmission pipelines at high pressures. At consumption regions, the pressure of natural gas is reduced in city gate stations(CGSs). Before the pressure reduction process, the temperature of natural gas is increased usually by using a water bath heater,which burns natural gas as fuel, to protect against freezing of natural gas. These types of heat exchangers have a low efficiency and consume a lot of fuel to generate the required heat. In the current study, the twisted configuration of the heating coil is proposed and investigated to enhance the heat transfer through a water bath heater with a nominal capacity of 1000 m^3·h^-1. Firstly, the implementation procedure is validated with data collected from the CGS of Qaleh-Jiq(located in Golestan province of Iran). A very good agreement is achieved between the obtained results and the real data. Then, three different twist ratios are considered to examine the twisting effects. The proposed technique is evaluated in the terms of velocity, temperature, and pressure variations, and the results are compared with the conventional case, i.e. straight configuration. It is found that both the heat transfer rate and the pressure drop augment as the twist ratio is raised. Finally, it is concluded that the twisted tubes can reduce the length of the gas coil by about 12.5% for the model with low twist ratio, 18.75% for the model with medium twist ratio, and 25% for the model with high twist ratio as compared to the straight configuration.

关键词： Natural gas city gate station Water bath heater heat transfer enhancement Twisted tube

Crack initiation stress and strain of jointed rock containing multi-cracks under uniaxial compressive loading: A particle flow code approach

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Journal of Central South University 2015年第2期22卷 638-645页

作者：范祥 KULATILAKE p h S W 陈新曹平 School of Resources and Safety Engineering Central South University Rock Mass Modeling and Computational Rock Mechanics Laboratories University of Arizona School of Mechanics and Civil Engineering China University of Mining and Technology (Beijing)

The ratio of crack initiation stress to the uniaxial compressive strength(SCI,B/SUC,B) and the ratio of axial strain at the crack initiation stress to the axial strain at the uniaxial compressive strength(B,UCB,CI,A,A/SSSS) were studied by performing numerical stress analysis on blocks having multi flaws at close spacing's under uniaxial loading using pFC3 D. The following findings are obtained: SCI,B/SUC,B has an average value of about 0.5 with a variability of ± 0.1. This range agrees quite well with the values obtained by former research. For joint inclination angle, β=90°,B,UCB,CI,A,A/SSSS is found to be around 0.48 irrespective of the value of joint continuity factor, k. No particular relation is found betweenB,UCB,CI,A,A/SSSS and β; however, the average B,UCB,CI,A,A/SSSS seems to slightly decrease with increasing k. The variability ofB,UCB,CI,A,A/SSSS is found to increase with *** on the cases studied in this work,B,UCB,CI,A,A/SSSS ranges between 0.3 and 0.5. This range is quite close to the range of 0.4to 0.6 obtained for SCI,B/SUC,B. The highest variability of ± 0.12 forB,UCB,CI,A,A/SSSS is obtained for k=0.8. For the remaining k values the variability ofB,UCB,CI,A,A/SSSS can be expressed within ± 0.05. This finding is very similar to the finding obtained for the variability of SCI,B/SUC,B.

关键词： jointed rock multi flaws uniaxial loading pFC3D model crack initiation stress(SCI B) axial strain at crack initiation

Experimental studies and phase field modeling of microstructure evolution during solidification with electromagnetic stirring

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中国有色金属学会会刊：英文版 2010年第S3期20卷 774-780页

作者： p.GERALD TENNYSON p.KUMAR h.LAKShMI G.phANIKUMAR p.DUTTA Department of Metallurgical and Materials Engineering Indian Institute of Technology National Facility for Semisolid Forming Department of Mechanical EngineeringIndian Institute of Science

Thixocasting requires manufacturing of billets with non-dendritic *** alloy A356 billets were produced by rheocasting in a mould placed inside a linear electromagnetic *** heat treatment was used to produce a transition from rosette to globular *** current and the duration of stirring were explored as control *** induction heating of the billet during stirring was quantified using experimentally determined thermal *** effect of processing parameters on the dendrite fragmentation was *** computational modeling of the process was performed using phase-field modeling of alloy solidification in order to gain insight into the process of morphological changes of a solid during this process.A non-isothermal alloy solidification model was used for *** morphological evolution under such imposed thermal cycles was simulated and compared with experimentally determined *** scaling using the thermosolutal diffusion distances was used to overcome computational difficulties in quantitative comparison at system *** results were interpreted in the light of existing theories of microstructure refinement and globularisation.

关键词： electromagnetic stirring non-dendritic phase field modeling microstructure

Assessment of soil erosion by RUSLE model using remote sensing and GIS-A case study of Nethravathi Basin

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Geoscience Frontiers 2016年第6期7卷 953-961页

作者： B.p.Ganasri h.Ramesh Department of Applied Mechanics & hydraulics National Institute of Technology Karnataka

Soil erosion is a serious problem arising from agricultural intensification, land degradation and other anthropogenic activities. Assessment of soil erosion is useful in planning and conservation works in a watershed or basin. Modelling can provide a quantitative and consistent approach to estimate soil erosion and sediment yield under a wide range of conditions. In the present study, the soil loss model, Revised Universal Soil Loss Equation （RUSLE） integrated with GIS has been used to estimate soil loss in the Nethravathi Basin located in the southwestern part of India. The Nethravathi Basin is a tropical coastal humid area having a drainage area of 3128 km2 up to the gauging station. The parameters of RUSLE model were estimated using remote sensing data and the erosion probability zones were determined using GIS. The estimated rainfall erosivity, soil erodibility, topographic and crop management factors range from 2948.16 to 4711.4 MJ/***-1hr-1/year, 0.10 to 0.44 t ha-1 -*** 1, 0 to 92,774 and 0 to 0.63 respectively. The results indicate that the estimated total annual potential soil loss of about 473,339 t/yr is comparable with the measured sediment of 441,870 t/yr during the water year 2002 2003. The predicted soil erosion rate due to increase in agricultural area is about 14,673.5 t/yr. The probability zone map has been derived by the weighted overlay index method indicate that the major portion of the study area comes under low probability zone and only a small portion comes under high and very high probability zone. The results can certainly aid in implementation of soil management and conservation practices to reduce the soil erosion in the Nethravathi Basin.

关键词： Soil erosion RUSLE Remote sensing GIS Nethravathi Basin

Mechanical thrombectomy in patients with M1 occlusion and NIhSS score≤5:a single-centre experience

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Stroke & Vascular Neurology 2016年第4期1卷 165-171页

作者： p Bhogal p Bucke O Ganslandt h Bazner h henkes M Aguilar perez Neuroradiological Clinic NeurocenterKlinikum StuttgartStuttgartGermany Neurological Clinic NeurocenterKlinikum StuttgartStuttgartGermany Neurosurgical Clinic NeurocenterKlinikum StuttgartStuttgartGermany Medical Faculty University Duisburg-EssenStuttgartGermany

Background:The recent success of several mechanical thrombectomy trials has resulted in a significant change in management for patients presenting with ***,it is still unclear how to manage patients that present with stroke and low National Institutes of health Stroke Scale(NIhSS)≤*** sought to review our experience of mechanical thrombectomy in patients with low NIhSS and confirmed M1 ***:We retrospectively analysed our prospectively maintained database of all patients undergoing mechanical thrombectomy between January 2008 and August *** identified 41 patients with confirmed M1 occlusion and low NIhSS(≤5)on admission to our *** collected demographic,radiological,procedural and outcome ***:The mean age of patients was 72±14,with 20 male *** medical conditions were common with hypertension seen in∼80%.Just over 50%presented with NIhSS 4 or *** average ASpECTS score on admission was 8.8(range 6–10),and the average clot length 10 *** Thrombolysis in Cerebral Infarction(TICI)≥2b was obtained in 87.8%of patients.7 patients had haemorrhage on follow-up,2 of which were *** 40 patients with 90-day follow-up,75%had modified Rankin Scale(mRS)score 0–*** were 3 deaths at 90 ***:Mechanical thrombectomy in patients with low NIhSS and proximal large vessel occlusion is technically possible and carries a high degree of success with good safety *** with low NIhSS and confirmed occlusion should be considered for mechanical thrombectomy.

关键词： patients occlusion throm

Minimal Length Quantum Mechanics of Dirac particles in Noncommutative Space

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Chinese physics Letters 2015年第3期32卷 1-4页

作者： A. N. Ikot h. p. Obong h. hassanabadi Theoretical physics Group Department of Physics University of Port Harcourt Choba PMB 5323 Nigeria Department of Basic Sciences Shahrood Branch Islamic Azad University Shahrood Iran

We study the two-dimensional harmonic oscillator in commutative and noncommutative space within the framework of minimal length quantum mechanics for spin-l^2 particles. The energy spectra and the eigenfunction are ob... 详细信息

关键词： length NC Minimal Length Quantum Mechanics of Dirac particles in Noncommutative Space GUp planck

A discrete model for response estimation of soil-structure systems with embedded foundations

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Earthquake Engineering and Engineering Vibration 2011年第2期10卷 263-276页

作者： p.Khodabakhshi h.Jahankhah M.A.Ghannad Department of Civil Engineering Sharif University of Technology

The need for simplified physical models representing frequency dependent soil impedances has been the motivation behind many researches throughout history. Generally, such models are generated to capture impedance functions in a wide range of excitation frequencies, which leads to relatively complex models. That is while there is just a limited range of frequencies that really influence the response of the structure. here, a new methodology based on the response-matching concept is proposed, which can lead to the development of simpler discrete models. The idea is then used to upgrade an existing simple model of surface foundations to the case of embedded foundations. The applicability of the model in both frequency domain and time domain analyses of soil-structure systems with embedded foundations is discussed. Moreover, the accuracy of the results is compared with another existing discrete model for embedded foundations.

关键词： discrete model embedded foundation spectral matching

Asymptotic iteration approach to supersymmetric bistable potentials

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Chinese physics B 2012年第1期21卷 68-73页

作者： h. Ciftci O. zer p. Roy Gazi niversitesi Fen-Edebiyat Fakültesi Fizik Blümü 06500 Teknikokullar-Ankara Turkey Department of Engineering physics Faculty of Engineering University of Gaziantep 27310 Gaziantep Turkey physics and Applied Mathematics Unit Indian Statistical Institute Calcutta 700035 India

We examine quasi exactly solvable bistable potentials and their supersymmetric partners within the framework of the asymptotic iteration method （AIM）. It is shown that the AIM produces excellent approximate spectra and that sometimes it is found to be more useful to use the partner potential for computation. We also discuss the direct application of the AIM to the Fokker-planck equation.

关键词： bistable potentials asymptotic iteration

Climate change and plague history in Europe

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Science China Earth Sciences 2018年第2期61卷 163-177页

作者： Ricci p.h.YUE harry F.LEE The Department of Geography The University of Hong Kong International Center for China Development Studies The University of Hong Kong

previous research that reported the linkage between climate change and plague activity primarily refers to the immediate effect of short-term climatic variation. Yet, decades of discussion about the climate-plague association cannot determine the precise role of climate in shaping plague dynamics. One reason for this discrepancy originates from the narrow selection of spatio-temporal settings for comprehensive analysis of the correlation, leading to a limited consideration of the complexity of possible *** analyzing a 414-year long record of plague outbreak in pre-industrial Europe and the corresponding climatic data in multi-scale,we find little evidence to support climate-plague correlation in(1) both climatic variations and large-scale climatic phenomena,(2)both country scale and continental scale,(3) annual to inter-annual scale, and(4) both linear and non-linear analytic approaches. The null-result should not be viewed as a general rejection of other recent findings related to climate-plague association; nevertheless,it suggests that a wider consideration of scales, sensitivity checks and consideration of contexts should be included in explaining and predicting plague transmission under contemporary global climate conditions.

关键词： plague Climate change Scale pre-industrial period Europe