检索结果-南通市图书馆

Stability of three-dimensional printable foam concrete as function of surfactant characteristics

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil engineering 2023年第6期17卷 935-947页

作者： Uday BODDEPALLI Indu Siva Ranjani GANDHI Biranchi PANDA department of Civil engineering Indian Institute of TechnologyGuwahatiAssam781039India Sustainable Resources for Additive Manufacturing(SReAM)Laboratory Department of Mechanical EngineeringIndian Institute of TechnologyGuwahatiAssam781039India

Extrudability is one of the most critical factors when designing three-dimensional printable foam *** extrusion process likely affects the foam stability which necessitates the investigation into surfactant properties particularly for concrete mixes with high foam *** many studies have been conducted on traditional foam concrete in this context,studies on three-dimensional printed foam concrete are *** address this research gap,the effects of surfactant characteristics on the stability,extrudability,and buildability of three-dimensional printed foam concrete mixes with two design densities(1000 and 1300 kg/m^(3))using two different surfactants and stabilizers(synthetic-based sodium lauryl sulfate stabilized with carboxymethyl cellulose sodium salt,and natural-based hingot surfactant stabilized with xanthan gum)were investigated in this *** density tests were conducted before and after the extrusion to determine stability of the foam *** results were then correlated with surfactant qualities,such as viscosity and surface tension,to understand the importance of key parameters in three-dimensional printing of foam *** on the experimental results,surfactant solu1tion with viscosity exceeding 5 m Pa·s and surface tension lower than 31 mN/m was recommended to yield stable three-dimensional printable foam concrete ***,the volume of foam in the mix significantly affected the printability *** traditional foam concrete,the variation in the stabilizer concentration and density of concrete were found to have insignificant effect on the fresh-state-characteristics(slump,slump flow,and static yield stress)and air void microstructure of the stable mixes.

关键词： foam concrete 3D printable concrete stability rheology air void microstructure

Simplification and Experimental Verification for Temperature and Humidity Field Coupling Model of Conservatory Soil

在线全文

学校读者我要写书评

暂无评论

Transactions of Tianjin University 2011年第1期17卷 33-38页

作者：曹滨斌李惟毅李兆力 School of mechanical engineering Tianjin University

Based on the surface energy balance model which is widely used abroad, a temperature and humidity field coupling model of conservatory soil without crop vegetation in full illumination was established. Considering the relatively closed environment in conservatory, weak solar radiation and little surface evaporation of soil, the daily variation of water content in different soil layers may be neglected, then the temperature and humidity field coupling model was simplified to a one-dimensional thermal diffusion model. The simplified model and the temperature and humidity field coupling model adopted the same computational method of soil physical parameters and discrete format of heat diffusion differential equations, and were applied to the continuous simulation of temperature field in conservatory soil without crop vegetation in full illumination. Through the comparison between simulation results and experimental data, the precision of the simplified model was verified. The typical rule of soil heat flux variation in a 24 h cycle was also obtained.

关键词： conservatory soil temperature humidity coupling model simplification

Effect of Gaussian size distribution width on minimum fluidization velocity in tapered gas–solid fluidized beds

在线全文

学校读者我要写书评

暂无评论

Particuology 2022年第7期20卷 71-84页

作者： Mojtaba Rasteh Goodarz Ahmadi S.H.Hosseini department of Chemical engineering Hamedan University of TechnologyHamedanP.O.Box 65155-579Iran department of mechanical and Aeronautical engineering Clarkson UniversityPotsdamNY 13699-5725USA department of Chemical engineering Ilam UniversityIlam 69315-516Iran

This paper investigated the effect of Gaussian distribution width,average particle diameter,particle loading,and the tapered angle on minimum fluidization velocity(U_(mf))by conducting extensive experiments in tapered fluidized *** powders with Gaussian size distribution and different distribution widths were used in the *** increase in U_(mf)with increasing the average particle diameter,particle loading,and the tapered angle was *** was also a nonmonotonic behavior of Umf as the Gaussian distribution width *** empirical correlation including dimensionless groups for predicting Umf in tapered beds was developed in which the effect of distribution width was *** proposed correlation predictions were in good agreement with the experimental data,with a maximum deviation of 16.5%and average and standard deviations of,respectively,6.4%and 7.4%.The proposed correlation was also compared with three earlier models,and their accuracy was discussed.

关键词： Tapered fluidized bed Minimum fluidization velocity Gaussian size distribution Distribution width Dimensional analysis

Numerical simulation of sediment deposition and trapping efficiency estimation in settling basins, considering secondary flows

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

International Journal of Sediment Research 2020年第4期35卷 347-354页

作者： Esmail Lakzian Hassan Saghi Omid Kooshki Center of Computational Energy Department of Mechanical EngineeringHakim Sabzevari University Aalto University Marine Technology department of Civil engineering Hakim Sabzevari University

In this paper,sediment deposition and trapping efficiency in shallow rectangular reservoirs were numerically estimated considering secondary *** order to do this,three dimensional(3D) steady,incompressible,Reynolds-averaged Navier-Stokes(RANS) equations with the standard κ-ε turbulence model were used as the governing *** drift-flux model also was used to model the solid *** the next step,the developed model was validated using the available *** it was used to simulate the sediment deposition and trapping efficiency in shallow rectangular reservoirs,considering secondary *** results show the sediment is trapped in the inlet corner of the reservoir,and two pairs of large vortices on the sides and two pairs of small vortices at the inlet corner of the reservoir are ***,the effects of the input angle of the reservoir to the trapping efficiency are evaluated and the results are discussed.

关键词： Sedimentation Deposition Secondary flows Numerical computation Trapping efficiency

A compliant polymorphing wing for small UAVs

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第10期33卷 2575-2588页

作者： Sadique P.MUHAMMED Rafic M.AJAJ Kamran AKHAN department of mechanical engineering United Arab Emirates UniversityAl Ain 15551United Arab Emirates department of Aerospace engineering Khalifa University of Science and TechnologyAbu Dhabi 127788United Arab Emirates

This paper presents the development of a novel compliant polymorphing wing capable of chord and camber morphing for small *** morphing wing can achieve up to 10%chord extension and±20°camber *** design,modeling,sizing,manufacturing and mechanical testing of the wing are *** polymorphing wing consists of one continuous front spar fixed to the fuselage and a rear spar on each side of the *** rear spar can translate in the chordwise direction(chord morphing)and rotate around itself(camber morphing).A flexible elastomeric latex sheet is used as the skin to cover the wing and maintain its aerodynamic shape whilst allowing *** loads from the skin are transferred to the spars using the compliant cellular ribs that support the flexible skin and facilitate ***-tensioning is applied to the skin to minimize wrinkling when subject to aerodynamic and actuation loads.A rack and pinion actuation system,powered by stepper motors,is used for ***-structural design,analysis and sizing are *** comparison between the polymorphing wing and the baseline wing(non-morphing)shows that chord morphing improves aerodynamic efficiency at low angles of attack while camber morphing improves efficiency at high angles of attack.

关键词： Camber morphing Chord morphing Compliant structures Flexible skin UAVs

NC Machining of Spiral Bevel Gear and Hypoid Gear Based on Unity Transformation Model

在线全文

学校读者我要写书评

暂无评论

Transactions of Tianjin University 2011年第4期17卷 264-269页

作者：王太勇邢元赵林李清 School of mechanical engineering Tianjin University

A unity transformation model (UTM) was presented for flexible NC machining of spiral bevel gears and hypoid gears. The model can support various machining methods for Gleason spiral bevel gears and hypoid gears, including generation machining and formation machining for wheel or pinion on a universal five-axis machining center, and then directly produce NC codes for the selected machining method. Wheel machining and pinion machining under UTM were simulated in Vericut 6.0 and tested on a five-axis machining center TDNC-W2000 with NC unit TDNC-H8. The results from simulation and real-cut verify the feasibility of gear machining under UTM as well as the correctness of NC codes.

关键词： spiral bevel gear NC machining unity transformation model

Charge distribution in graphene from quantum calculation

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第1期27卷 479-485页

作者：梁泽芬马生凌薛红涛樊丁 Jingbo Louise Liu 汤富领 department of Materials Science and engineering Lanzhou University of TechnologyState Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals department of mechanical and Electrical engineering Lanzhou Institute of Technology department of Chemistry Texas A&M University

The local charge distributions of different shape graphene sheets are investigated by using the quantum calculations. It is found that the charge distribution on carbon atom is not uniform, strongly depending on its position in the graphene and its local atomic environment condition. The symmetrical characteristic and geometrical structures of graphene also have an important influence on the charge distribution. The charges of atom at the graphene edge are strongly related to their surrounding bonds. It is found that the charges of double-bonded atom at the zigzag edge are closely related to the bond angle, but the charges of double-bonded atom at the armchair edge are mainly influenced by the area of triangle. The charges of triple-bonded atom at the edge are mainly affected by the standard deviation of the length of the associated triple bonds.

关键词： graphene charge distribution geometry

Fabrication and Characterization of TiAl Alloy by Fields Activated Sintering Technology(FAST)

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2022年第3期37卷 470-474页

作者： ZHOU Liming WU Mingxia QIN Yuan YANG Gang YANG Yi School of mechanical engineering Chengdu UniversityChengdu 610106China School of mechanical engineering Sichuan UniversityChengdu 610065China

Ti-47Al alloy was fabricated by multi-physical fields activated sintering technology(FAST).With the coupling effects of electrical and pressure fields as the dominant driving force,a nearly fulldensity(relative density:99.15%)TiAl alloy sample was *** microstructural characterizations,phase transformation at different sintering temperatures and their contributions to mechanical properties were *** results reveal that TiAl_(3)is the main phase when sintered at 600 and 700℃.When the sintering temperature reaches 800℃,the main phases are TiAl and Ti_(3)*** the increase of sintering temperature,the content of TiAl increases and that of Ti_(3)Al *** the sintering temperature reaches 1000℃,the alloy with fine and uniform microstructure and good mechanical properties can be obtained.

关键词： TiAl alloy Micro-FAST Microstructure mechanical properties

Effect of Stress-Dependent Thermal Conductivity on Thermo-mechanical Coupling Behavior in GaN-Based Nanofilm Under Pulse Heat Source

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2021年第1期34卷 27-39页

作者： Qicong Li Xiaoya Tang Linli Zhu Haihui Ruan department of engineering Mechanics and Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceZhejiang UniversityHangzhou310027China department of mechanical engineering The Hong Kong Polytechnic UniversityHong KongChina

The thermal properties of a nanostructured semiconductor are affected by multi-physical fields,such as stress and electromagnetic fields,causing changes in temperature and strain *** this work,the influence of stress-dependent thermal conductivity on the heat transfer behavior of a GaN-based nanofilm is *** finite element method is adopted to simulate the temperature distribution in a prestressed nanofilm under heat *** results demonstrate the effect of stress field on the thermal conductivity of GaN-based nanofilm,namely,the prestress and the thermal stress lead to a change in the heat transfer behavior in the *** the same heat source,the peak temperature of the film with stress-dependent thermal conductivity is significantly lower than that of the film with a constant thermal conductivity and the maximum temperature difference can reach 8.2 *** results could be useful for designing GaN-based semiconductor devices with higher reliability under multi-physical fields.

关键词： Multi-physical effect Stress-dependent thermal conductivity Prestress fields Heat transfer behavior GaN-based nanofilm Finite element method