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Experimental and numerical study on the shrinkage-deformation of carrot slices during hot air drying

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International Journal of Agricultural and Biological Engineering 2023年第1期16卷 260-272页

作者： Dalong Jiang Congcong Li Zifan Lin Yuntian Wu Hongjuan Pei Magdalena Zielinska Hongwei Xiao School of Computer and Control Engineering Yantai UniversityYantai 264005ShandongChina Hebei Agricultural University Baoding 071001HebeiChina Hebei Key Laboratory of Agricultural Big Data Baoding 071001HebeiChina Department of Electrical and Electronic Engineering University of Western AustraliaPerth 6000Australia BeiGene Guangzhou Biologics Manufacturing Co. LtdGuangzhou 510555China Neuroscience and Intelligent Media Institute Communication University of ChinaBeijing 100024China Department of Systems Engineering University of Warmia and MazuryOlsztyn 004889Poland College of Engineering China Agricultural UniversityBeijing 100083China

In order to further understand the mechanism of material volume change in the drying process,numerical simulations(considering or neglecting shrinkage)of heat and mass transfer during convective drying of carrot slices under constant and controlled temperature and relative humidity were carried out.Simulated results were validated with experimental data.The results of the simulation show that the Quadratic model fitted well to the moisture ratio and the material temperature data trend with average relative errors of 5.9%and 8.1%,respectively.Additionally,the results of the simulation considering shrinkage show that the moisture and temperature distributions during drying are closer to the experimental data than the results of the simulation disregarding shrinkage.The material moisture content was significantly related to the shrinkage of dried tissue.Temperature and relative humidity significantly affected the volume shrinkage of carrot slices.The volume shrinkage increased with the rising of the constant temperature and the decline of relative humidity.This model can be used to provide more information on the dynamics of heat and mass transfer during drying and can also be adapted to other products and dryers devices.

关键词： carrot drying numerical simulation heat and mass transfer shrinkage

Exploring the Mechanical Properties,shrinkage and Compensation Mechanism of Cement Stabilized Macadam-Steel Slag from Multiple Perspectives

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Journal of Renewable Materials 2023年第5期11卷 2513-2529页

作者： Wei Zhang Mulian Zheng Yifeng Li Wuxi Zheng Key Laboratory for Special Area Highway Engineering of Ministry of Education Chang’an UniversityXi’an710064China Rizhao Transportation Management Center Rizhao27680China Central-South Safety&Environment Technology Institute Co. Ltd.Wuhan43000China

Steel slag is characterized by high strength,good wear resistance and micro-expansion.This study aims at exploring the potential of steel slag in cement stabilized aggregates,mainly including mechanical properties,shrinkage and compensation mechanisms.For this purpose,the compressive strength and compressive resilient modulus of cement stabilized aggregates with different steel slag contents(CSMS)were initially investigated.Subsequently,the effects of steel slag and cement on dry shrinkage,temperature shrinkage,and total shrinkage were analyzed through a series of shrinkage test designs.Additionally,in combination with X-ray diffraction(XRD)and Scanning electron microscope(SEM),the characteristic peaks and microscopic images of cement,steel slag and cement-steel slag at different hydration ages were analyzed to identify the chemical substances causing the expansion volume of steel slag and reveal the compensation mechanism of CSMS.The results show that the introduction of 20%steel slag improved the mechanical properties of CSMS by 16.7%,reduced dry shrinkage by 21%,increased temperature shrinkage by 5.8%and reduced its total shrinkage by 19.2%.Compared with the hydration reaction of cement alone,the composite hydration reaction of steel slag with cement does not produce new hydrates.Furthermore,it is noteworthy that the volume expansion of the f-CaO hydration reaction in steel slag can compensate for the volume shrinkage of cement-stabilized macadam.This research can provide a solid theoretical basis for the application and promotion of steel slag in cement-stabilized macadam and reduce the possibility of shrinkage cracking.

关键词： Cement stabilized macadam-steel slag compensate mechanical properties pavement base shrinkage steel slag

shrinkage of magnetosphere observed by TC-1 satellite during the high-speed solar wind stream

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Science China(Technological Sciences) 2008年第10期51卷 1695-1703页

作者： H. RME I. DANDOURAS C. M. CARR Centre d'Etude Spatiale des Rayonnements BP 4346 31028 Toulouse cedex 4 France The Blackett Laboratory Imperial College London SW7 2BZ UK

During the interval 06:14―07:30 UT on August 24, 2005, since the Earth’s magneto- pause was suddenly compressed by the persistent high-speed solar wind stream with the southward component of the interplanetary magnetic field (IMF), the magnetopause moved inward for about 3.1 RE. Meanwhile, TC-1 satellite shifted from northern plasma sheet to the northern lobe/mantle region, although it kept inward flying during the interval 06:00―07:30UT. The shift of TC-1 from the plasma sheet to the lobe/mantle is caused by the simultaneous inward displacements of the plasma sheet and near-Earth lobe/mantle region, and their inward movement velocity is larger than the inward motion velocity of TC-1. The joint inward dis-placements of the magnetopause, the lobe/mantle region and the plasma sheet indicate that the whole magnetosphere shrinks inward due to the magnetospheric compression by the high-speed solar wind stream, and the magnetospheric ions are attached to the magnetic field lines (i.e. ‘frozen’ in magnetic field) and move inward in the shrinking process of magnetosphere. The large shrinkage of magne-tosphere indicates that the near-Earth magnetotail compression caused by the strong solar wind dynamic pressure is much larger than its thickening caused by the southward component of the IMF, and the locations of magnetospheric regions with different plasmas vary remarkably with the variation of the solar wind dynamic pressure.

关键词： solar wind dynamic pressure shrinkage of magnetosphere storm sudden commencement substorm

shrinkage Behavior of High Performance Concrete at Different Elevated Temperatures under Different Sealing Conditions

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Journal of Wuhan University of Technology(Materials Science) 2006年第3期21卷 138-141页

作者：潘志华 NAKAMURA Hidemi WEE Tionghuan College of Materials Science & Engineering Nanjing University of TechnologyNanjing 210009China Research and Development Center Taiheiyo Cement CorporationChiba 285-8655Japan Department of Civil Engineering National University of SingaporeSingapore

The shrinkage behavior of high performance cement concrete made from Portland cement, ultra fine granulated blast furnace slag and pulverized fly ash with addition of superplasticizer at different temperatures from ambient temperature to 120 ℃ under different seuliug conditions was investigated by means of length change measurement on cylindrical concrete specimens along with curing age. Results show that drying shrinkage deformations of titled concrete specimens increased rapidly as the curing temperature rose. The development of dryiing shrinkage deformatian can be efficiently controlled with the aid of aluminum tape sealing as compared with the unsealed specimens, especially when the curing temperature is below 60℃ , although it will increase dramatically when the curing temperature is elevated to above 90%＂ . Polymer coating on concrete specimens showed a similar effect on the control of drying shrinkage as the sealing operation with aluminum tape.

关键词： high performance concrete shrinkage granulated blast-furnace slag fly ash elevated temperature sealing condition

shrinkage Reducing Measures for Engineering Cementitious Composites

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Journal of Wuhan University of Technology(Materials Science) 2008年第6期23卷 907-911页

作者：杨英姿 School of Civil Engineering Harbin Institute of Technology China Building Materials Academy

Inhibition measurement of shrinkage of engineering cementitious composites （ECC） was investigated due to typical ECC with higher free drying shrinkage.The effects of expanded admixture （EA）,shrinkage reducing admixture （SRA）,coarse sand＋stone powder （CS＋SP） and superabsorbent polymer （SAP） on drying shrinkage and mechanical properties were studied.The experimental results show that ECC incorporating EA,SRA and coarse sand can retain around 60% of the typical ECC＇s free drying shrinkage.Superabsorbent polymerl（SAP） can delay the development of free drying shrinkage of ECC at different ages,and the effect of SAP is not distinct like the actions of EA,superabsorbent polymer（SRA） and coarse sand.Significantly,SAP may act as artificial flaw to form a more homogeneous defect system that increases the potential of saturated multiple cracking,hence the ductility of ECC will be improved greatly.

关键词： engineered cementitious composites （ECC） shrinkage SAP

Salinity effects on soil shrinkage characteristic curves of fine-grained geomaterials

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第1期11卷 181-191页

作者： Partha Narayan Mishra Alexander Scheuermann Thierry Bore Ling Li School of Civil Engineering University of Queensland

Fine-grained clayey soils are prone to substantial volume changes during desiccation in response to the dynamics of their moisture regime,and are of critical importance in several geotechnical and geoenvironmental engineering applications. As such, the complex interactions between the fraction of soil solids and the ionic pore fluid play a critical role in governing such volume changes, and have been the focus in studies dealing with marine geotechnology, mine-tailing ponds, engineered barrier systems, etc.With this in mind, the present investigation evaluates the volume changes and accompanying densification from a saturated slurry state to a constant volume state of a reference fine-grained geomaterial,kaolin, subjected to evaporative dewatering. For this purpose, several parametric studies involving determination of soil shrinkage characteristic curves(SSCCs) of kaolin under the influence of varied salt constituents and concentrations of pore fluid are performed. Furthermore, a critical assessment of SSCCs depicting progressive shrinkage and volume change behaviour of geomaterials is provided, followed by the analysis of experimentally obtained SSCCs of the kaolin to explore the impacts of pore fluid salinity.Moreover, the SSCCs are parameterised with a predictive model and the fitting parameters are used to quantitatively demonstrate the salinity-dependent volume change response of a representative finegrained porous system.

关键词： Kaolin Pore fluid salinity Soil shrinkage curves Pore space dynamics Geotechnical engineering

Pre-reinforcement grout in fractured rock masses and numerical simulation for optimizing shrinkage stoping configuration

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Journal of Central South University 2017年第12期24卷 2924-2931页

作者：于少峰吴爱祥王贻明李涛 School of Civil and Resource Engineering University of Science and Technology Beijing Beijing 100083 China Key Laboratory of High-Efficient Mining and Safety of Metal of Ministry of Education University of Science and Technology Beijing Beijing 100083 China

Proper room and pillar sizes are both critical factors for safe mining and high ore recovery rate in shrinkage stoping mining of underground metal mines. The rock masses of Tangdan copper mine of China are fractured, which needs much reinforcement and support prior to mining. Cement-sodium silicate grout technology was selected, then its related parameters such as grout pressure, diffusion radius and time were calculated and proposed. In order to test the effect of the pressured grout in the fractured No.4 ore block, field experiments were conducted. To optimize stoping configuration, three-dimensional numerical simulation with ANSYS and FLAC 3 D softwares was proposed. The results show that the drilling porosity and mechanical properties of the rock masses are increased obviously. After grout, ore recovery rate is increased by 10.2 % employing the newly designed stoping configuration compared with the previous. Last, analyzed from the surface movements, roof subsidence and the maximum principal stress of the pillars, the mining safety is probable of being ensured.

关键词： shrinkage stoping mining cement-sodium silicate grout effect of pressured grout stoping configuration three-dimensional numerical simulation

Contribution of CNTs/CNFs morphology to reduction of autogenous shrinkage of Portland cement paste

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Frontiers of Structural and Civil Engineering 2016年第2期10卷 224-235页

作者： Feneuil BLANDINE Karin HABERMEHI-CWIRZEN Andrzej CWIRZEN Concrete Technology Laboratory Department of Civil and Structural Engineering School of Engineering Aalto University Rakentajanaukio 4 00076 Aalto Finland Department of Civil Environmental and Natural Resources Engineering Luled University of Technology Luled Sweden

ABSTRACT In this experimental study, carbon nanotubes （CNTs） and carbon nanofibers （CNFs） were dispersed by intensive sonication in water in the presence of superplasticizer and subsequently mixed with Portland cement with water/ cement ratios varying between 0.3 and 0.4. The autogenous shrinkage in the fresh stage was investigated. The CNTs and CNFs were characterized by high resolution scanning electron microscopy （SEM） and the hydrated pastes were studied by X-ray diffraction and SEM. The results showed a reduction of the autogenous shrinkage by 50% for pastes containing small amounts （0.01 wt%） of nanomaterials. Higher additions appeared to be less effective. The highest reduction of shrinkage was observed for carbon nanofibers which were long, rather straight and had diameters of around 200 nm. The result showed that the addition of nanomaterials accelerated the hydration processes especially in the early stages of hydration. The effect was the most pronounced in the case of functionalized nanotubes. The proposed mechanism resulting in the reduction of the autogenous shrinkage was a combination of nano-reinforcing effects, alterations of hydration and microstructure of the hydrated matrix.

关键词： carbon nanotubes shrinkage cement paste

Numerical Simulation of Macrosegregation Caused by Thermal–Solutal Convection and Solidification shrinkage Using ALE Model

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Acta Metallurgica Sinica(English Letters) 2019年第11期32卷 1396-1406页

作者： Kang-Xin Chen Hou-Fa Shen Key Laboratory for Advanced Materials Processing Technology Ministry of Education School of Materials Science and Engineering Tsinghua University

Solidifi cation shrinkage has been recognized as an important factor for macrosegregation formation. An arbitrary Lagrangian–Eulerian(ALE) model is constructed to predict the macrosegregation caused by thermal–solutal convection and solidi-fi cation shrinkage. A novel mesh update algorithm is developed to account for the domain change induced by solidifi cation shrinkage. The velocity–pressure coupling between the non-homogenous mass conservation equation and momentum equation is addressed by a modifi ed pressure correction method. The governing equations are solved by the streamline-upwind/Petrov–Galerkin-stabilized fi nite element algorithm. The application of the model to the Pb-19.2 wt%Sn alloy solidifi cation problem is considered. The inverse segregation is successfully predicted, and reasonable agreement with the literature results is obtained. Thus, the ALE model is established to be a highly effective tool for predicting the macrosegregation caused by solidifi cation shrinkage and thermal–solutal convection. Finally, the effect of solidifi cation shrinkage is analyzed. The results demonstrate that solidifi cation shrinkage delays the advance of the solidifi cation front and intensifi es the segregation.

关键词： Macrosegregation Solidification shrinkage Finite element method Arbitrary Lagrangian–Eulerian(ALE)