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An investigation into the properties of ternary and binary cement pastes containing glass powder

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Frontiers of structural and Civil Engineering 2019年第3期13卷 741-750页

作者： Marcelo frota BAZHUNI Mahsa KAMALI Ali GHAHREMANINEZHAD Department of Civil Architectural and Environmental EngineeringUniversity of MiamiCoral GablesFL 33146USA

The properties of binary and ternary cement pastes containing glass powder (GP) were *** at early age was evaluated using semi-adiabatic calorimetry and at late ages using non-evaporable water content and thermogravimetric *** transport characteristic was assessed by measuring electrical *** binary paste with slag showed the highest hydration activity compared to the binary pastes with GP and fly ash (FA).The results indicated that the pozzolanic behavior of the binary paste with GP was less than that of the binary pastes with slag or FA at late *** increase in the electrical resistivity and compressive strength of the binary paste with GP compared to other modified pastes at late ages was *** was shown that GP tends to increase the drying shrinkage of the *** pastes containing GP did not exhibit synergistic enhancements compared to the respective binary pastes.

关键词： cement paste glass powder pozzolanic reaction supplementary cementitious material

Flow, thermal criticality and transition of a reactive third-grade fluid in a pipe with Reynolds' model viscosity

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Journal of Hydrodynamics 2016年第1期28卷 84-94页

作者： samuel s.OKOYA Department of Mathematics Obafemi Awolowo University

Neglecting the consumption of the material, a steady incompressible flow of an exothermic reacting third-grade fluid with viscous heating in a circular cylindrical pipe is numerically studied for both cases of constant viscosity and Reynolds＇ viscosity model. The coupled ordinary differential equations governing the flow in cylindrical coordinates, are transformed into dimensionless forms using appropriate transformations, and then solved numerically. solutions using Maple are presented in tabular form and given in terms of dimensionless central fluid velocity and temperature, skin friction and heat transfer rate for three parametric values in the Reynolds＇ case. The numerical results for the velocity and temperature fields are also presented through graphs. Bifurcations are discussed using shooting method. Comparisons are also made between the present results and those of previous work, and thus verify the validity of the provided numerical solutions. Important properties of thermal criticality are provided for variable viscosity parameter and reaction order. Further numerical results are presented in the form of tables and graphs for transition of physical parameters, while varying certain flow and fluid material parameters. Also, the flow behaviour of the reactive fluid of third-grade is compared with those of the Newtonian reactive fluid.

关键词： non-Newtonian fluids third-grade fluid thermal transition heat generation temperature dependent viscosity numerical solutions

Hydraulic jump and choking of flow in pipe with a change of slope

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Journal of Hydrodynamics 2022年第6期34卷 1044-1066页

作者： Rui Zeng s.samuel Li Department of Building Civil and Environmental EngineeringConcordia UniversityMontrealCanada

This paper investigates hydraulic jumps in sloping pipes by means of wall-resolved large eddy simulation(LEs).The purpose is to achieve an improved understanding of jump behaviours driven by pipe discharge and *** LEs model predicts the hydraulic jump as a 3-D two-phase flow,with air as the gas phase and water as the liquid *** predictions yield instantaneous velocity and pressure fields as well as fluid volume *** instantaneous flow variables allow ensemble averages,which quantify the internal structures and integral properties of the hydraulic *** predicted instantaneous velocity shows spectra in consistency with the well-known Kolmogorov−5/3 *** ensemble averages of air and water velocities,free-surface profile,roller length and aeration length,compare well with available experimental *** jump behaviours are *** aspects such as free-surface fluctuation and jump-toe oscillation resemble the classical hydraulic jump on horizontal *** like the 3-D distributions of core jet,vorticity and aeration are much more *** on the pipe discharge and slope,the resulting jump can be a complete or an incomplete *** incomplete hydraulic jump causes choked flow *** has severe consequences on drainage conditions in sewer pipes laid on sloping *** paper proposes using the Okubo-Weiss parameter as a new way to subtly delineate the region of hydraulic *** is much more efficient and less ambiguous,compared with traditional visual inspections.

关键词： Hydraulic jump sloping pipe two-phase bubbly flow large eddy simulation(LEs) choking of flow Okubo-Weiss parameter

Analysis of sampling Error Uncertainties and Trends in Maximum and Minimum Temperatures in China

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Advances in Atmospheric sciences 2014年第2期31卷 263-272页

作者： HUA Wei samuel s.P.sHEN WANG Huijun Nansen-Zhu International Research Centre Institute of Atmospheric Physics Chinese Academy of Sciences Department of Atmospheric sciences Chengdu University of Information Technology University of the Chinese Academy of sciences Department of Mathematics and statistics San Diego State University

In this paper we report an analysis of sampling error uncertainties in mean maximum and minimum temperatures （Tmax and Tmin） carried out on monthly,seasonal and annual scales,including an examination of homogenized and original data collected at 731 meteorological stations across China for the period *** of the gridded data and national average,linear trends and their uncertainties,as well as the homogenization effect on uncertainties are *** is shown that the sampling error variances of homogenized Tmax and Tmin,which are larger in winter than in summer,have a marked northwest-southeast gradient distribution,while the sampling error variances of the original data are found to be larger and *** and Tmin increase in all months of the year in the study period 1951-2004,with the largest warming and uncertainties being 0.400℃ （10 yr）-1 ＋ 0.269℃ （10 yr）-1 and 0.578℃ （10 yr）-1 ＋ 0.211℃ （10 yr）-1 in February,and the least being 0.022℃ （10 yr）-1 ＋ 0.085℃ （10 yr）-1 and 0.104℃ （10 yr）-1 ＋0.070℃ （10 yr）-1 in *** can remove large uncertainties in the original records resulting from various non-natural changes in China.

关键词： sampling error uncertainty maximum temperature minimum temperature temperature trend

Reduced graphene oxide supersonically sprayed on wearable fabric and decorated with iron oxide for supercapacitor applications

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Journal of Materials science & Technology 2021年第23期82卷 47-56页

作者： Ali Aldalbahi Edmund samuel Bander s.Alotaibi Hany El-Hamshary sam s.Yoon Department of Chemistry College of ScienceKing Saud UniversityRiyadh11451Saudi Arabia school of Mechanical Engineering Korea UniversitySeoul136-713Republic of Korea

We demonstrate the fabrication of wearable supercapacitor *** electrodes were applied to wearable fabric by supersonically spraying the fabric with reduced graphene oxide(r GO)followed by decoration with iron oxide(Fe_(2)O_(3))nanoparticles via a hydrothermal *** integration of iron oxide with r GO flakes on wearable fabric demonstrates immense potential for applications in high-energystorage *** synergetic impact of the intermingled r GO flakes and Fe_(2)O_(3) nanoparticles enhances the charge transport within the composite electrode,ultimately improving the overall electrochemical *** advantage of the porous nature of the fabric,electrolyte diffusion into the active r GO and Fe_(2)O_(3) materials was significantly enhanced and subsequently increased the electrochemical interfacial *** effect of the Fe_(2)O_(3) concentration on the overall electrochemical performance was *** optimal composition yields a specific capacitance of 360 F g^(-1) at a current density of 1 Ag^(-1) with a capacitance retention rate of 89%after 8500 galvanostatic cycles,confirming the long-term stability of the Fe_(2)O_(3)/r GO fabric electrode.

关键词： supersonic spraying Conductive textile Wearable energy devices Reduced graphene oxide Iron oxide supercapacitor

Nanomaterials for renewable hydrogen production,storage and utilization

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Progress in Natural science:Materials International 2012年第6期22卷 522-534页

作者： samuel s.Mao shaohua shen Liejin Guo Lawrence Berkeley National Laboratory and Department of Mechanical Engineering University of California at Berkeley.BerkeleyCA 94720United States Lawrence Berkeley National Laboratory and Department of Mechanical Engineering University of California at Berkeley.BerkeleyCA 94720.United States International Research Center for Renewable Energy.state Key Laboratory of Multiphase Flow in Power Engineering.Xi'an Jiaotong University International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong University

An ever growing demand for energy coupled with increasing pollution is forcing us to seek environmentally clean alternative energy resources to substitute fossil *** rapid development of nanomaterials has opened up new avenues for the conversion and utilization of renewable *** article reviews nanostructured materials designed for selected applications in renewable energy conversion and *** review is based on the authors’ research,with particular focus on solar hydrogen production,hydrogen storage and hydrogen *** topics include photoelectrochemical(PEC) water splitting and photocatalytic hydrogen production, solid-state hydrogen storage,and proton exchange membrane fuel cells(PEMFCs).It is expected that the rational design of nanomaterials could play an important role in achieving a renewable energy based economy in the coming decades.

关键词： Nanomaterials Renewable energy Hydrogen production Fuel cell Hydrogen storage

Black TiO_(2) for solar hydrogen conversion

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Journal of Materiomics 2017年第2期3卷 96-111页

作者： Bin Wang shaohua shen samuel s.Mao school of science MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed MatterState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China International Research Centre for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityShaanxi710049China Xi'an Jiaotong University suzhou Academy SuzhouJiangsu215123China Department of Mechanical Engineering University of California at BerkeleyBerkeleyCA94720United States samuel Mao Institute of New Energy Science Hall1003 Shangbu RoadShenzhen518031China

Titanium dioxide(TiO_(2))has been widely investigated for photocatalytic H_(2) evolution and photoelectrochemical(PEC)water splitting since ***,its wide bandgap(3.0-3.2 eV)limits the optical absorption of TiO_(2) for sufficient utilization of solar *** TiO_(2) has been proposed as an effective strategy to enhance its solar absorption and thus the photocatalytic and PEC activities,and aroused widespread research *** this article,we reviewed the recent progress of black TiO_(2) for photocatalytic H_(2) evolution and PEC water splitting,along with detailed introduction to its unique structural features,optical property,charge carrier transfer property and related theoretical *** summarized in this review article,black TiO_(2) could be a promising candidate for photoelectrocatalytic hydrogen generation via water splitting,and continuous efforts are deserved for improving its solar hydrogen efficiency.

关键词： Black TiO_(2) Photoelectrochemical water splitting Photocatalytic Hydrogen evolution

Analytical modeling and simulation of germanium single gate silicon on insulator TFET

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Journal of semiconductors 2014年第3期35卷 25-28页

作者： T.s.Arun samuel N.B.Balamurugan Department of Electronics and Communication Engineering Thiagarajar College of Engineering

This paper proposes a new two dimensional（2D） analytical model for a germanium（Ge） single gate silicon-on-insulator tunnel field effect transistor（sG sOI TFET）. The parabolic approximation technique is used to solve the 2D Poisson equation with suitable boundary conditions and analytical expressions are derived for the surfacepotential,*** is derived further by using the electric fields. The results show that Ge based TFETs have significant improvements ***heanalytical model results with the technology computer aided design（TCAD） simulation results and also comparing them with results from a silicon based TFET.

关键词： tunnel field effect transistor(TFET) analytical modelling Poisson equation surface potential electric field

CFD evaluation of pressure drop across a 3-D filter housing for industrial gas turbine plants

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Frontiers in Energy 2016年第2期10卷 192-202页

作者： Fidelis I. ABAM samuel O. EFFIOM Olayinka s. OHUNAKIN Department of Mechanical Engineering Michael Okpara University ofAgriculture Umudike Umuahia 02155 Nigeria Department of Mechanical Engineering Cross River University ofTechnology Calabar 540252 Nigeria Department of Mechanical Engneering Covenant Universiy Ota 11 O01Nigeria

This paper investigated the flow distribution and total pressure drop across a designed 3-D filter housing integrated with a 3-stage filtration system using computa- tional fluid dynamics （CFD）. The filter housing model was proposed for a heavy-duty industrial gas turbine plant operating at an average ambient temperature of 20℃.The pressure drops across the classes of filters were 652.8 Pa, 2692.2 Pa, 887.8 Pa, 776.2 Pa and 2304.2 Pa for I-GB, GB-GA, GA-FA, FA-HA, and HA-O, respectively. The results obtained indicated an acceptable total pressure drop of 7.2% for the entire filter housing before filter clean-up. Although the CFD simulation result shows that small outlet flow velocity and transonic flows exist at the outlet of the filter housing, the designed filter housing was proved compatible with the studied GT, for inlet flow conditions between 600≤ Wair≤610 kg/s and 60≤Vair≤70 m/s for the air flow rate and velocity, respectively. Furthermore, the designed filter housing could be adopted for the studied GT and locations of Usan and Maiduguri in Nigeria, and other locations with similar environmental conditions.

关键词： computational fluid dynamics (CFD) pressure drop flow distribution filter housing gas turbine