Volume expansion rate of the Lorentzian manifold based on integral Ricci curvature over a timelike geodesic

Oxidization of diamond in the sintering process of diamond/borosilicate glass composites would result in low compressive fracture strength (CFS) of the grit and uncontrolled expansion with many irregular pores in the composites, causing low bending strength of the tools. In this paper diamond/borosilicate glass composites were prepared by cold pressing and sintering at 850 C for 120 min in air. An active element Zn was incorporated into the composites in order to resolve the above issues. The effects of Zn contents on the properties of the composites was investigated by the bending strength tests, the volume expansion rate tests, differential scanning calorimeter test (DSC), thermogravimetry (TG), X-ray diffraction analysis (XRD), and scanning electron microscope (SEM). The results showed Zn was oxidized and then converted to ZnAl2O4 and Zn2SiO4 phases during sintering. The bending strength improved and the expansion phenomenon was inhibited for the composites with various Zn additions. The maximum bending strength and minimum volume expansion rate were obtained for the composite GZ8. This Zn content resulted in a decrease of volume expansion rate from 8.57% to -20.53%, and an increase in bending strength from 28.49 MPa to 74.02 MPa compared with the composite GZ0. The CFS results of the diamond grits separated from GZ0 and GZ8 was 21N and 26N, respectively.

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Hydration and Expansion Properties of Novel Concrete Expansive Agent

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.405-406.267 ◽

2009 ◽

Vol 405-406 ◽

pp. 267-271

Author(s):

Pei Wei Gao ◽

Fei Geng ◽

Xiao Lin Lu

Keyword(s):

Particle Size ◽

Volume Expansion ◽

Curing Temperature ◽

Expansion Rate ◽

The Novel ◽

Expansive Agent ◽

Novel Agent

The hydration and expansive characterization of a novel concrete expansive agent were investigated in this paper. The results showed that the hydration activities of the novel agent depended on the calcining temperature, particle size and curing temperature. When the expansive agent was mixed in concrete, the early shrinkage of concrete was reduced. If the content and distribution of the expansive agent in concrete is appropriate and uniform, the expansion rate of concrete may be controlled, and the shrinkage of concrete could be compensated effectively by the gentle volume expansion.

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Influence of leg position and environmental temperature on segmental volume expansion during venous occlusion plethysmography

Clinical Science ◽

10.1042/cs20020257 ◽

2003 ◽

Vol 104 (6) ◽

pp. 599-605 ◽

Cited By ~ 13

Author(s):

Lennart JORFELDT ◽

Torbjörn VEDUNG ◽

Elisabeth FORSSTRÖM ◽

Jan HENRIKSSON

Keyword(s):

Blood Flow ◽

Strain Gauge ◽

Volume Expansion ◽

Venous Blood ◽

Venous Occlusion ◽

Transmural Pressure ◽

Sympathetic Tone ◽

Venous Occlusion Plethysmography ◽

Expansion Rate ◽

Leg Position

Blood flow determinations by venous occlusion plethysmography applying the strain-gauge technique are frequently used. A problem with the strain-gauge technique is that the relationship between venous volume and transmural pressure is not linear and, furthermore, changes with the sympathetic tone. The present study tests the hypothesis that these factors lead to a redistribution of venous blood, which may impair the accuracy of the technique. The relative volume expansion rates of four leg segments were studied with the leg in different positions and at disparate temperatures, thereby inducing varying venous pressures and sympathetic tone (n=6). With elevated leg and relaxed veins (at 50 °C), the distal thigh showed a relatively low expansion rate (25.8±4.5 ml·min-1·l-1), whereas values in the calf segments were higher (34.5–39.0 ml·min-1·l-1). With lower initial transmural pressure, calf segments can increase their volume much more during occlusion compared with the distal thigh. In a higher transmural pressure region (lowered leg), the difference in compliance between limb segments is less. In this case, compliance and volume expansion rate was higher in the distal thigh (14.2, 13.5 and 22.2 ml·min-1·l-1 at 10, 20 and 50 °C respectively) than in the calf segments (for the distal calf: 6.4, 7.7 and 16.2 ml·min-1·l-1 respectively). There was a significant interaction (P<0.001) between temperature and leg position, indicating a higher degree of sympathetic vasoactivity in the calf. It is concluded that blood flow determination by strain-gauge plethysmography is less accurate, due to a potential redistribution of the venous blood. Therefore possible influences of variations in sympathetic tone and venous pressure must be considered even in intra-individual comparisons, especially in interventional studies.

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The Influence of Curing Temperature on the Coordination of the Expansion and Strength of High Strength Expansive Concrete

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.539.205 ◽

2013 ◽

Vol 539 ◽

pp. 205-210

Author(s):

Jing Jing Feng ◽

Cui Ling Zhou ◽

Yong Sun ◽

Xiao Qing Wang

Keyword(s):

Pore Structure ◽

Volume Expansion ◽

High Strength ◽

Curing Temperature ◽

Expansion Rate ◽

Early Hydration ◽

Expansive Concrete ◽

Age Appropriate ◽

Curing Condition ◽

The Relationship

The influence of curing temperature on the relationship between the expansion and the strength was studied. The results showed that under the standard curing condition (20。C), the expansion and strength of the high strength expansive concrete develop unisonously with the prolongation of age. However, under the high curing temperature, there is a conflict between the expansion and strength of the concrete. Elevated curing temperature (40。C) promotes the hydration of expensive agent and cement. However the quickly developing strength of the concrete limits its expansion, and leads to the lowest restricted expansion rate of the concrete at 40。C. But suitable expansion made the microstructure of the concrete denser, which resulted in the highest strength of the concrete at 40。C. High curing temperature (60。C) leads to excessive expansion at early hydration age. Appropriate volume expansion is benefit to the improvement of pore structure of hardened paste by reducing large pores and to increase the strength of the concrete. However, excessive volume expansion is harmful to the microstructure and leads to the lowest strength of the concrete at 60。C.

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Volume comparison between spacelike hypersurfaces in a Lorentzian manifold with integral Ricci curvature bounds

General Relativity and Gravitation ◽

10.1007/s10714-010-1106-1 ◽

2010 ◽

Vol 43 (8) ◽

pp. 2089-2102 ◽

Cited By ~ 1

Author(s):

Seong-Hun Paeng

Keyword(s):

Ricci Curvature ◽

Lorentzian Manifold ◽

Volume Comparison ◽

Curvature Bounds ◽

Spacelike Hypersurfaces

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