scholarly journals Sustainable High-Performance Hydraulic Concrete

2022 ◽  
Vol 14 (2) ◽  
pp. 695
Author(s):  
Lei Wang ◽  
Shengwen Tang ◽  
Terasa E. Chen ◽  
Wengui Li ◽  
Chamila Gunasekara
Keyword(s):  
High Performance ◽  
Hydraulic Structures ◽  
Hydraulic Concrete

Concrete has always been indispensable as a material for the engineering and construction of hydraulic structures (e [...]

Application of Superfine Aggregate in Corrosion Resist of Hydraulic Concrete

2014 ◽  
Vol 599 ◽  
pp. 3-6
Author(s):  
Jun Ci ◽  
Zhao Xiong Sun ◽  
Yi Xiong Ge
Keyword(s):  
High Performance ◽  
Erosion Resistance ◽  
High Performance Concrete ◽  
Sulfate Attack ◽  
Corrosion Mechanism ◽  
Hydraulic Concrete ◽  
Super Plasticizer

According to the vulnerable erosion ability of the ordinary hydraulic concrete, we adopt the method which adding both with superfine slag and super plasticizer to form the high performance concrete.The experiment about concrete erosion was carried out between the high performance concrete and the ordinary hydraulic concrete, the corrosion mechanism was studied respectively from the macro perspective and the micro perspective.From the experiment results we can conclude that the high performance concrete can resistance the sulfate attack which with the SO42- concentration almost reached 20250 mg/L,it has better erosion resistance than the ordinary hydraulic concrete.

Experimental Research and Numerical Analysis of Type Selection of Fiber for High Performance Hydraulic Concrete

2011 ◽  
Vol 83 ◽  
pp. 85-90
Author(s):  
Jun Yong He ◽  
Xiao Qing Huang ◽  
Cheng Yu Tian
Keyword(s):  
Shear Stress ◽  
Experimental Research ◽  
High Performance ◽  
Interfacial Shear Stress ◽  
Basalt Fiber ◽  
Interfacial Shear ◽  
Polyacrylonitrile Fiber ◽  
Type Selection ◽  
Hydraulic Concrete ◽  
Fiber Concrete

Basalt fiber has the advantages of non-pollution and omnipotence, and expected to be widely used in the 21st Century. Therefore, more and more attention is paid on experimental research of the basalt fiber in the world. Firstly, according to the type selection principles and requirements of the fibers used in the hydraulic concrete, the contrast testing of the plastic shrinkage between fiber cement mortar and pure mortar is made. The experimental results showed that basalt fiber, polypropylene fiber and polyacrylonitrile fiber can be preliminarily chosen as reinforced fibers in high performance hydraulic concrete. Secondly, the impacts of the suggested three sorts of fibers on the interfacial shear stress of the fiber concrete are analyzed by numerical simulation，which showed that maximum interfacial shear stress of the basalt fiber concrete is minimum. So, the bond strength between basalt fiber and concrete is the best. Finally, taking both characteristics of basalt fiber and the increase of concrete costs into account, it can be concluded that top priority should be given to the basalt fiber rather than to other fibers for high performance hydraulic concrete.

scholarly journals Analysis of Abrasion Depth and Rates in Concrete

2021 ◽  
Vol 15 (6) ◽  
pp. 1
Author(s):  
Mohammed Saleh AlAnsari
Keyword(s):  
Comparative Analysis ◽  
High Performance ◽  
High Performance Concrete ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Hydraulic Structures ◽  
Polypropylene Fibers ◽  
New Techniques ◽  
Different Types ◽  
High Performance Fiber

Abrasion is a major problem in hydraulic structures as they are continuously exposed to various types of water. Henceforth, these structures are susceptible to damage and require heavy maintenance. There is a significant demand in finding new techniques for improving the resistance towards the erosion of the concrete used in the construction of hydraulic structures. This work put forth a comparative analysis of the performance of two different types of concretes towards resistance namely, high-performance fiber reinforced concrete (HPFRC) [steel fibers (30 mm and 50 mm) and polypropylene fibers (19 mm)] and high-performance concrete (HPC). A comparative study was carried out based on their resistance towards wearing and hydro-abrasion erosion. The analyses were conducted using the WMP ECLIPSE method and ASTM C 1138 method. The results indicated that the rate of abrasion could be diminished by 18% based on the types of cement, fibers, concrete and modifications like the addition of silica fume. 

A High Performance Energy Analyzer for Use in Electron Scanning Microscopy

1969 ◽  
Vol 27 ◽  
pp. 14-15
Author(s):  
A. V. Crewe ◽  
M. Isaacson ◽  
D. Johnson
Keyword(s):  
High Performance ◽  
Vertical Plane ◽  
Median Plane ◽  
Electron Gun ◽  
Uniform Field ◽  
Loss Mechanism ◽  
Electron Scanning Microscopy ◽  
Sector Type ◽  
Double Focusing ◽  
Electron Energy Loss

A double focusing magnetic spectrometer has been constructed for use with a field emission electron gun scanning microscope in order to study the electron energy loss mechanism in thin specimens. It is of the uniform field sector type with curved pole pieces. The shape of the pole pieces is determined by requiring that all particles be focused to a point at the image slit (point 1). The resultant shape gives perfect focusing in the median plane (Fig. 1) and first order focusing in the vertical plane (Fig. 2).

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

Use of the Magnetostatic Analogue In Electromagnetic Lens Engineering

1970 ◽  
Vol 28 ◽  
pp. 360-361
Author(s):  
John W. Coleman
Keyword(s):  
Boundary Conditions ◽  
High Performance ◽  
Force Fields ◽  
Optical Design ◽  
Direct Conversion ◽  
Design Engineering ◽  
Design Data ◽  
Scalar Potentials ◽  
Geometric Elements ◽  
At Will

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.

Prospects for convergent beam electron diffraction with a 200kV cold field-emission transmission electron microscope

1991 ◽  
Vol 49 ◽  
pp. 466-467
Author(s):  
J W Steeds ◽  
R Vincent
Keyword(s):  
Field Emission ◽  
High Performance ◽  
Small Diameter ◽  
Convergent Beam Electron Diffraction ◽  
Zone Axis ◽  
Medium Voltage ◽  
Transmission Electron ◽  
Good Crystallinity ◽  
Special Modification ◽  
Convergent Beam

We review the analytical powers which will become more widely available as medium voltage (200-300kV) TEMs with facilities for CBED on a nanometre scale come onto the market. Of course, high performance cold field emission STEMs have now been in operation for about twenty years, but it is only in relatively few laboratories that special modification has permitted the performance of CBED experiments. Most notable amongst these pioneering projects is the work in Arizona by Cowley and Spence and, more recently, that in Cambridge by Rodenburg and McMullan.There are a large number of potential advantages of a high intensity, small diameter, focussed probe. We discuss first the advantages for probes larger than the projected unit cell of the crystal under investigation. In this situation we are able to perform CBED on local regions of good crystallinity. Zone axis patterns often contain information which is very sensitive to thickness changes as small as 5nm. In conventional CBED, with a lOnm source, it is very likely that the information will be degraded by thickness averaging within the illuminated area.

Current State of Biological High-Resolution Scanning Electron Microscopy

1988 ◽  
Vol 46 ◽  
pp. 180-181 ◽  
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Performance ◽  
Low Voltage ◽  
Backscattered Electrons ◽  
Lens Position ◽  
Low Voltage Operation ◽  
Signal Collection ◽  
Probe Size ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

A new generation of high performance field emission scanning electron microscopes (FSEM) is now commercially available (JEOL 890, Hitachi S 900, ISI OS 130-F) characterized by an "in lens" position of the specimen where probe diameters are reduced and signal collection improved. Additionally, low voltage operation is extended to 1 kV. Compared to the first generation of FSEM (JE0L JSM 30, Hitachi S 800), which utilized a specimen position below the final lens, specimen size had to be reduced but useful magnification could be impressively increased in both low (1-4 kV) and high (5-40 kV) voltage operation, i.e. from 50,000 to 200,000 and 250,000 to 1,000,000 x respectively.At high accelerating voltage and magnification, contrasts on biological specimens are well characterized1 and are produced by the entering probe electrons in the outmost surface layer within -vl nm depth. Backscattered electrons produce only a background signal. Under these conditions (FIG. 1) image quality is similar to conventional TEM (FIG. 2) and only limited at magnifications >1,000,000 x by probe size (0.5 nm) or non-localization effects (%0.5 nm).

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

Improved 3-D reconstruction using stereo computer graphics and multiple tilt EM images

1995 ◽  
Vol 53 ◽  
pp. 630-631
Author(s):  
Lee D. Peachey ◽  
Lou Fodor ◽  
John C. Haselgrove ◽  
Stanley M. Dunn ◽  
Junqing Huang
Keyword(s):  
Computer Graphics ◽  
High Performance ◽  
Transverse Section ◽  
Three Dimensional ◽  
Stereo Pair ◽  
3D Reconstructions ◽  
Video Cameras ◽  
Biological Objects ◽  
Microscope Images ◽  
High Performance Computer

Stereo pairs of electron microscope images provide valuable visual impressions of the three-dimensional nature of specimens, including biological objects. Beyond this one seeks quantitatively accurate models and measurements of the three dimensional positions and sizes of structures in the specimen. In our laboratory, we have sought to combine high resolution video cameras with high performance computer graphics systems to improve both the ease of building 3D reconstructions and the accuracy of 3D measurements, by using multiple tilt images of the same specimen tilted over a wider range of angles than can be viewed stereoscopically. Ultimately we also wish to automate the reconstruction and measurement process, and have initiated work in that direction.Figure 1 is a stereo pair of 400 kV images from a 1 micrometer thick transverse section of frog skeletal muscle stained with the Golgi stain. This stain selectively increases the density of the transverse tubular network in these muscle cells, and it is this network that we reconstruct in this example.

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