scholarly journals Application of Nanoindentation and 2D and 3D Imaging to Characterise Selected Features of the Internal Microstructure of Spun Concrete

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1016 ◽  
Author(s):  
Jarosław Michałek ◽  
Michał Pachnicz ◽  
Maciej Sobótka
Keyword(s):  
Cross Section ◽  
Longitudinal Axis ◽  
Concrete Mixture ◽  
Wall Structure ◽  
Outer Side ◽  
Micro Computed Tomography ◽  
Concrete Element ◽  
The Cross ◽  
Paste Content ◽  
Spun Concrete

The spinning of concrete is a process in which concrete mixture is moulded and compacted under the action of the centrifugal force arising during the fast rotational motion of the mould around its longitudinal axis. As a result of the spinning of the liquid concrete mixture, an element annular in cross section, characterised by an inhomogeneous layered wall structure, is produced. The heavier constituents tend towards the cross-section wall’s outer side, while the lighter components tend towards its inner side. The way in which the particular constituents are distributed in the element’s cross section is of key importance for the macro properties of the manufactured product. This paper presents procedures for investigating spun concrete and interpreting the results of such investigations, which make it possible to characterise the microstructure of the concrete. Three investigative methods were used to assess the distribution of the constituents in the cross section of the element: micro-computed tomography (µCT), 2D imaging (using an optical scanner) and nanoindentation. A procedure for interpreting and analysing the results is proposed. The procedure enables one to quantitatively characterise the following features of the microstructure of spun concrete: the mechanical parameters of the mortar, the aggregate content, the pore content, the cement paste content, the aggregate grading and the size (dimensions) of the pores. Special attention is devoted to the determination of the variation of the analysed quantities in the cross section of the element. The result of the application of the investigative procedures is presented for an exemplary spun concrete element. The proposed procedures constitute a valuable tool for evaluating the process of manufacturing spun concrete elements.

scholarly journals Transport Performance of a Steeply Situated Belt Conveyor

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7984
Author(s):  
Leopold Hrabovský ◽  
Jiří Fries
Keyword(s):  
Cross Section ◽  
Longitudinal Axis ◽  
Conveyor Belt ◽  
Angle Of Repose ◽  
Material Distribution ◽  
Belt Conveyor ◽  
Working Surface ◽  
The Cross

The paper presents a methodology for determining the volume of a batch of conveyed material located before a transverse partition of a certain height and the distance over which the batch of material extends on the working surface of the conveyor belt along its longitudinal axis. Knowing the geometric dimensions of the transported batch of material makes it possible to appropriately set the spacing of the belt cleats and thereby to optimally determine the conveying performance of the inclined belt conveyor. When the angle of inclination of a conveyor with a straight idler frame is equal to the angle of surcharge of the conveyed material, then no layer of material is carried on the surface of the belt. If the conveyor belt is guided along a trough idler frame, only the lower cross-section of the filling of material is used. An increase in the cross-section of the belt load of a conveyor inclined at an angle, which exceeds the angle of repose of the conveyed material, can be achieved by installing regularly spaced belt cleats around the circumference of the working surface of the endless loop of the conveyor belt. The volume of the batch of material retained by the belt cleat depends on the height and width of the cleat and whether or not the conveyor belt is provided with corrugated side edges. The paper presents theoretically determined relationships that can be used to determine the size of the transverse and longitudinal area and the volume of the batch of material spread on the surface of the conveyor belt in front of the cleat. The experiments performed provide the distances of the material distribution on the surface of the conveyor belt depending on the height of the cleat and the angle of inclination of the conveyor belt.

scholarly journals NUMERICAL SIMULATION OF THE BROKEN ROCK MASS TRANSPORTATION IN A ROTATING PIPELINE

2021 ◽  
Vol 2 (4) ◽  
pp. 141-150
Author(s):  
Guil Nam Khan ◽  
Evgeny P. Rusin
Keyword(s):  
Cross Section ◽  
Bulk Material ◽  
Longitudinal Axis ◽  
Pneumatic Conveying ◽  
Discrete Elements ◽  
Cross Sectional ◽  
Horizontal Pipe ◽  
Angular Velocities ◽  
The Cross ◽  
The Impact

The impact of the angular velocity of a horizontal pipe rotating around its longitudinal axis and the shape of its cross-section on the efficiency of pneumatic conveying of bulk material in it has been numerically investigated by the discrete elements method. The maximum number of non-contact particles, that is, particles being not in contact with other material particles and with the pipe, in the cross section of the pipe during one its revolution, is assumed the condition for effective pneumatic conveying. A method for searching for non-contact particles is proposed, which makes it possible to calculate their number at fixed pipe position angles during its rotation. For various cross-sectional shapes, the optimal angular velocities are determined at which the average number of non-contact particles in the cross-section is maximum. The results of the study can be used to increase the productivity of the removal of products of destruction when drilling horizontal boreholes in rocks and soils.

scholarly journals THE SECOND STAGE OF STRESSED-DEFORMED CONDITION OF REINFORCED CONCRETE STRUCTURES WHEN TURNING WITH BENDING (CASE 2)

2019 ◽  
Vol 15 (4) ◽  
pp. 66-82 ◽  
Author(s):  
Vladimir Kolchunov ◽  
Aleksey Demyanov ◽  
Николай Наумов
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Strain State ◽  
Longitudinal Axis ◽  
Concrete Element ◽  
Second Stage ◽  
Tangential Forces ◽  
Shaped Crack ◽  
Derivatives Of ◽  
Spatial Section

It is proposed a complex resistance computational model of reinforced concrete constructions in build­ings and structures under the action torsion with bending. It consists of from the block near the support (formed by a spatial crack and a compressed concrete zone closed by it - a spatial section k) and a second block, which is formed by a vertical cross section I-I passing perpendicularly to the longitudinal axis of the reinforced concrete element along the edge of the compressed zone, which closes the spatial spiral-shaped crack. The case when the greatest influence on the stress-strain state of structures has the effect of torque is considered (case 2). In this case, as the calculated forces are taken into account in the spatial section: normal and tangential forces in the concrete of the compressed zone; components of axial and “dowel” efforts in the working reinforcement, inter­sected by a spiral spatial crack. The resolving equations are constructed that form a closed system and the La­grange function is unified. Using the partial derivatives of the constructed function with respect to all the varia­bles entering into it and equating them to zero, an additional system of equations is constructed. The dependence is obtained after the corresponding algebraic transformations, that allows us to search for the projection of a dan­gerous spatial crack.

Partial Union of Acute Scaphoid Fractures

2005 ◽  
Vol 30 (5) ◽  
pp. 440-445 ◽  
Author(s):  
H. P. SINGH ◽  
D. FORWARD ◽  
T. R. C. DAVIS ◽  
J. S. DAWSON ◽  
J. A. ONI ◽  
...  
Keyword(s):  
Cross Section ◽  
Longitudinal Axis ◽  
The Other ◽  
Ct Scans ◽  
Fracture Union ◽  
Scaphoid Fractures ◽  
Initial Injury ◽  
Wrist Function ◽  
The Cross ◽  
Plaster Immobilization

Sixty-six patients with acute scaphoid fractures were treated non-operatively in a below elbow plaster for 8 to 12 weeks and underwent CT scans along the longitudinal axis of the scaphoid at 12 to 18 weeks. These scans showed that 14 fractures had not united and that 30 had united throughout the whole cross-section of the scaphoid. The other 22 had partially united with bridging trabeculae in some areas of the cross-section. These 22 partial unions were graded as 0% to 24% union (0 cases), 25% to 49% union (5 cases), 50% to 74% union (7 cases), and 75% to 99% union (10 cases). The 12 patients who had less than 75% fracture union were followed-up further and nine underwent another CT scan at 23 to 40 weeks after the initial injury. These showed union across the whole of the cross-section of the fracture in seven cases and 75% to 99% union in the other two cases, who had full and painless wrist function. We conclude that partial union of the scaphoid is a common occurrence but, in most cases, it progresses to full union without the need for prolonged plaster immobilization.

Analysis of Stress and Strain in the Equal Channel Angular Drawing Process

2006 ◽  
Vol 526 ◽  
pp. 19-24 ◽  
Author(s):  
Javier León ◽  
C.J. Luis-Pérez
Keyword(s):  
Plastic Strain ◽  
Cross Section ◽  
Three Dimensional ◽  
Longitudinal Axis ◽  
Wire Drawing ◽  
Stress And Strain ◽  
Drawing Process ◽  
The Cross ◽  
High Plastic Strain ◽  
High Plastic

The equal channel angular drawing (ECAD) process is an innovative method to obtain materials with high plastic strain in a continuous way. This deformation is higher than the deformation achieved by a conventional wire drawing process, for the same reduction of the cross section, so if an adequate thermal treatment is employed later, it could be possible to obtain an initial material with high value that could be useful in conventional manufacturing processes. This process consists in drawing a material through a die where two circular channels intersect at an angle between 90º and 135º. In this work a study using finite element of the plastic strain and the stresses that appear for one aluminium alloy AA-1370 has been carried out. Two ECAD passes have been made, where for the second pass the billet has been rotated 180º along the longitudinal axis. Finally, a calibrated pass has been carried out in order to obtain the billet with homogeneous dimensions in all the cross section. All the simulations have been calculated at room temperature and by using good conditions of lubrication. In order to perform the FEM simulations, a three dimensional geometry has been used. To analyze by FEM the second ECAD pass and the calibration pass, the deformations and stresses achieved in the previous passes have been taken into consideration. This has been done with the aim of achieving higher accuracy. Moreover, a comparative analysis with experimental results has been carried out.

A New Approach to the Demonstration of Oxidase-Localization Using Tannic Acid Or Catechin

1973 ◽  
Vol 31 ◽  
pp. 698-699
Author(s):  
V. Mizuhira ◽  
Y. Futaesaku
Keyword(s):  
Cross Section ◽  
Tannic Acid ◽  
Elastic Fiber ◽  
The Other ◽  
New Approach ◽  
Tissue Block ◽  
Active Reaction ◽  
The Cross

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.

Energy Distribution in Electron Beams

1972 ◽  
Vol 30 ◽  
pp. 568-569
Author(s):  
Tamotsu Ohno
Keyword(s):  
Electron Beam ◽  
Energy Distribution ◽  
Cross Section ◽  
Integral Curve ◽  
Electron Beams ◽  
Electron Gun ◽  
Angular Divergence ◽  
Apparent Increase ◽  
Integral Width ◽  
The Cross

The energy distribution in an electron; beam from an electron gun provided with a biased Wehnelt cylinder was measured by a retarding potential analyser. All the measurements were carried out with a beam of small angular divergence (<3xl0-4 rad) to eliminate the apparent increase of energy width as pointed out by Ichinokawa.The cross section of the beam from a gun with a tungsten hairpin cathode varies as shown in Fig.1a with the bias voltage Vg. The central part of the beam was analysed. An example of the integral curve as well as the energy spectrum is shown in Fig.2. The integral width of the spectrum ΔEi varies with Vg as shown in Fig.1b The width ΔEi is smaller than the Maxwellian width near the cut-off. As |Vg| is decreased, ΔEi increases beyond the Maxwellian width, reaches a maximum and then decreases. Note that the cross section of the beam enlarges with decreasing |Vg|.

Research in the cross-section of community psychology and global climate change: A call for action

2009 ◽  
Author(s):  
Marci Culley ◽  
Holly Angelique ◽  
Courte Voorhees ◽  
Brian John Bishop ◽  
Peta Louise Dzidic ◽  
...  
Keyword(s):  
Climate Change ◽  
Cross Section ◽  
Global Climate Change ◽  
Community Psychology ◽  
Global Climate ◽  
The Cross

Experimental Studies Of Multilayer Glass Structures On Compression, Compression With Bending And Simple Bending

2019 ◽  
pp. 22-30
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Applied Load ◽  
Experimental Studies ◽  
Strength Properties ◽  
Research Topic ◽  
Normative Values ◽  
Laminated Glass ◽  
The Cross ◽  
Experimental Values

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.

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