Search results

There is significant experimental evidence to show that S-N curves are strongly dependent on the microstructure of the material, such as grain size, porosity and other defects, and as a result, S-N curves often exhibit significant scatter [3-5].
To understand the statistical variability of fatigue results, a number of studies have been carried out to establish an optimum experimental procedure for measuring S-N behaviour.
The replication levels are dependent on the number of stress amplitude levels (L) tested and the number of specimens (ns) used in the testing program, and are characterized by the percent replication (PR) that can be calculated by [2,6]: (1) ASTM E739 recommends replication levels of 17-33% for developing preliminary data and 75-88% for developing reliability data.
Fig 2b shows clearly that while the linear relationships based on percent replications of 45% and 50% are the same, the improvements from replication are minimal although the number of specimens used was doubled.
With such a small number of specimens available and to keep the replication requirements for particular purpose, e.g. 33 – 50% for research and development and 50 – 75% for design allowable data tests, the tested stress levels will be constrained and as a result, may not be enough to detect the whole picture of the S-N curves.

As the price of reform, one of reforms, the government has increased the purchase price of grain, cotton, oil, fuel, and other 18 kinds of agricultural products and the ex-factory price of coal, iron ore, pig iron, steel ingots, billets, non-ferrous metals, cement and other industrial products.
Gradual momentum of the faster rate appreciation after the 2006 year, and gradually formed a firm expectation of RMB appreciation, so that made a large number of international capital flow into the country.
Affected by the U.S. financial crisis, the global financial crisis, China's economy has suffered a serious impact, at the same time, the exports dropped sharply, a large number of import and export enterprises are facing a severe test, unemployment has risen sharply.
Journal of Economic Perspectives, Volume 3, Number 3, Summer 1989, Pages 51-77
Journal of Economic Perspectives-Volume 12, Number 1—Winter 1998—Pages 27-36

The microstructure is composed of relatively dense structure with grain size d < 1µm and nanosized pores confirming gas adsorption results.
Fig. 1 SEM microphotographies of BCP ceramic granules In vivo evaluation of control group animal bone samples showed decreased number of long, thin bone trabeculae intermixed by bone marrow.
Also the number of osteocytes was notably decreased.
IHC evaluation of experimental group bone samples presented stably increased number of OC positive cells more than twice in all cases as to compare to the control (Fig. 2).
However, increase in number of OP containing osteocytes was less obvious.

Higher speed reduces grain boundaries, facilitating electron transmission and increasing film crystallinity [9], inducing π-π stacking for improved molecular structure.
The FTIR software calculated the absorption peak areas, representing the number of chemical bonds.
Figure 8 shows the increased number of Quinoid molecules in the high-resistance state facilitates an easier transformation to the low-resistance state after irradiation.
Devices adjusted in the process exhibit prolonged data retention time due to an increased number of conduction paths formed by Quinoid molecules, surpassing other control groups over time.
The physical property results from FTIR confirm an increase in the number of Quinoid functional groups in the PI film.

Introduction The number of civil transport aircrafts that comes to the end of the initial design life is continuously increasing Worldwide.
The wing panels under study were fabricated in laminated plates, in such a manner that the longitudinal orientation of the grains is collinear with the longitudinal direction of the wing.
Fig. 3 : Normalised S-N curves expressed as the ratio of the maximum stress divided by ultimate tensile stress as a function of the number of cycles to failure.
However, the large number of facets and their presence sometimes far from the initiation site suggest that they cannot systematically correspond with a sub-layer initiation process.
In addition, no clear trend can be found in the number of facets, their density or their surface, as a function of the studied material.

Describing the rock crushing process from fractal point as follows: rock mass broken into subset blocks with finite number and similar shape .Some of these subset blocks has been broken into more subset blocks with similar shape .And each time for repeating this process has produced smaller blocks .According to the probability and similar ratio of rock broken and the volume for different grain size, it can be drawn: Fund: This article is funded by the National Natural Science Foundation of China(rock damage evolution under Hydraulic fracturing and forming mechanism of micro-cracks No. 50974028) 3 0 bD k k R y R −   =     (1) Where: yk--accumulation volume ratio which fragmentation less than or equal to Rk; Db--fractal dimension of broken blocks [1].
The fractal dimension calculation of rock mass damage and fragmentation So far the sieving method is used to calculate the fractal dimension of rock mass damage fragmentation, but a great number of labor power and material resources will be spent.
The calculation of rock damage variables After rock broken, there are a large number of internal cracks, pores and other microscopic structures.
Where λstands for the mathematical expectation of the damage volume element number per unit volume.
According to Poisson's law, which is satisfied by the probability of damage volume elements, it can be drawn the probability with no damage in the volume V, and probability density of rock damage volume element can be gained: ( ) V V e λψ λ −= (4) If using Di to represent the rock damage variable, if we make λ=1/Va , the following formula can be established: ( ) ( ) ( ) 0 0 1 1 1 1 d a d m m V Vd V a i V V m V e V V dV V D V e V V dV λ ψ λ ψ − −   − +    = = − + ∫ ∫ (5) Where:Vm--The bulk volume of the rock, m3; Vd--The damage volume of the rock，m3;Va--The average volume of broken rock，m3;λ--The number of rock joints and cracks[3].

With the ad-dition of SOD, the icorr value (moving electrons) will increase due to the number of electrons flowing more and more.
The auxiliary elec-trode will measure the number of electrons received using a Galvanometer measur-ing device.
With the addition of SOD values, the oxidation reaction will be more and more so that the number of electrons flowing will be more and more.
The number of oxidation reactions in the working electrode also shows the number of detached atoms that show the corrosion that occurs.
[5] Wu, Z., Yu, F., Zhang, P., Liu, X.: Micro-mechanism study on rock breaking behavior under water jet impact using coupled SPH-FEM/DEM method with Voronoi grains.

These were carried out in 0.01 M NaCl and 0.1 M Na2SO4 aqueous solutions, after mounting the samples as electrodes, in order to permit comparisons with results in the literature for 318 Journal Title and Volume Number (to be inserted by the publisher) other magnesium alloys, e.g. [3].
The only feature to notice is the increase in peak intensities of the Mg2Si phase and a decrease of its full width at half height (grain size increasing).
Units] Journal Title and Volume Number (to be inserted by the publisher) 319 (a) (b) Fig. 2.
These pits were even detected (in small number) in the samples tested with the less aggressive sodium sulphate solution.
Journal Title and Volume Number (to be inserted by the publisher) 321 Conclusions The experimental results shows that the corrosion resistance of the Mg60Ti10Si30 alloy is higher than that of Mg88Ti5Si7, which is explained in terms of chemical composition and changes in the alloy microstructure occurred during milling and subsequent heat treatment.

Choosing Experimental Samples and Numbering In order to study on impact resistance performance and test method of PDC, five common typical macro-interfaces (planar structure, v-groove, u-groove, ring groove, ring claw-tooth) are used as objects of this study.
Table 1 Samples’ serial number and their picture Number 1# 2# 3# 4# 5# Interface Planar structure v-groove u-groove Ring groove Ring claw-tooth Picture The Research for Test Methods of PDC Impact Resistance The impact resistance performance of PDC indicates its comprehensive performance, and is of crucial importance to PDC application effect.
Table 2 Test result of PDC impact resistance at normal temperature Samples number Interface structure Impact frequency Total impact energy 1# planar structure 20 78.4 2# v-groove 45 176.4 3# T-groove 70 274.4 4# Ring groove 90 352.8 5# Ring claw-tooth 130 509.6 During the drilling process of PDC tooth, there are two critical temperatures for the tooth’s thermal wear, 350°C and 750°C.
Table 3 Test result of the impact resistance performance of PDC after heating Samples number Heating temperature(℃) Heating time (min) Impact frequency Total impact energy Change of impact Energy (%) 1# 750 1 15 58.8 -25 2# 750 1 37 145.0 -17.8 3# 750 1 60 235.2 -14.3 4# 750 1 77 301.8 -14.4 5# 750 1 118 462.6 -9.2 SEM Test and EDAX Test Result for Interface Structure Through SEM photos and analyzing elements on PCD axis by EDAX, we can observe the combination state of interface structures.
Most of grain boundaries in diamond have formed D-D combination, which makes the psychical combination between WC-Co and diamond becomes a chemical combination WC-Co-D.

Micro particles of clay possess a very large specific surface area, and a large number of charges are assembled on the particle surfaces, with the result that electric potential on the particle surface is generally in the range from tens to hundreds of mV[2].
Besides, in a thin film flow, while the film thickness is less than ten-molecule-thick layer (about 5 nm), the equivalent viscosity coefficient of polarity water will depend generally on the number of molecule layers and can be increased by 105 times[3].
Pore solutions in the samples are NaCl solutions with different molar concentration, which means the number of moles of solute dissolved in one liter of solution.
Table 1 Geotechnical Properties of the Samples Used in Tests Composition Number e0 ρd (g/cm3) w (%) Averagediameter() CEC cmol/kg Total surface area ( m2/g) Outer surface area ( m2/g) Charge density C/m2 Plasticity index Ip ( %) 1-1 1.64 0.94 67.3 2.5 73.5 456 39.8 0.1554 00％ Bentonite 1-2 1.61 0.96 67.0 93.7 2-1 1.62 0.95 65.8 2-2 1.63 0.95 66.3 3-1 1.66 0.94 66.0 3-2 1.65 0.94 65.4 4-1 1.64 0.94 63.8 4-2 1.63 0.95 64.1 5-1 1.63 0.95 63.3 5-2 1.63 0.95 63.4 Table 2 Permeability Coefficient from the Seepage Consolidation Test Results Number NaCl solution concentration ni (mol) Consolidation coefficient Cv(cm2/s) permeability coefficient ka (cm/s) Average permeability coefficient (cm/s) 1-1 0 1.88E-4 5.04E-08 4.89E-08 1-2 1.85E-4 4.75E-08 2-1 8.3E-3 1.77E-4 4.98E-08 5.08E-08 2-2 1.76E-4 5.17E-08 3-1 8.3E-2 1.09E-4 5.18E-08 5.22E-08 3-2 1.41E-4 5.25E-08 4-1 8.3E-1 1.70E-4 8.42E-08 8.23E-08 4-2 1.70E-4 8.03E-08 5-1 2 1.03E-3 5.13E-07 5.10E-07 5-2 1.03 E-3 5.06E
In coarse grained soils, the thickness of the diffuse double layer is much less than the effective pore diameter and has little effects on the flow of pore water, thus hardly creating MEFES.