THE CALCULATION OF THE DENSITY FIELD FROM AXISYMMETRIC SCHLIEREN INTERFEROGRAMS BY THE IMAGE PROCESSING TECHNIQUES

The schlieren interferograms used to be analyzed in a qualitative way. In this paper, by means of the powerful computational ability and the large memory of computer; the image processing method is investigated for the digitalization of an axisymmetric schlieren interferogram and the determination of the density field. This method includes the 2-D low-pass filtering, the thinning of interferometric fringes, the extraction of physical information and the numerical integration of the density field. The image processing results show that the accuracy of the quantitative analysis of the schlieren interferogram can be improved and a lot of time can be saved in dealing with optical experimental results. Therefore, the algorithm used here is useful and efficient.

Study on traveling magnetic field casting of sheet components

The distribution of a magnetic field over an inductor used for sheet castings has been investigated experimentally.With an increase in height from the surface, the magnetic field density decreases according to the exponential law.In the transverse direction, the magnetic field density is approximately uniform except near the edges.The magnetic field density is direct proportional to the number of turns multiplied by the current in amperes.Ferro-magnetic material in the upper mould can enhance the magnetic field density.Under the electromagnetic force, the mould-filling process of sheet casings has been studied by physical simulation method.The difference in filling capability between gravity casting and travelling magnetic field casting has been studied.The electromagnetic force can enhance the filling process, but it also brings a problem.With an increase in the magnetic field density, the surface quality of the aluminum alloy sheet castings becomes poor.The reason is discussed.

As Regards the Speed in a Medium of the Electromagnetic Radiation Field

The velocity of the electromagnetic radiation in a perfect dielectric, containing no charges and no conduction currents, is explored and determined on making use of the Lorentz transformations. Besides the idealised blackbody radiation, whose vacuum propagation velocity is the universal constant c, being this value independent of the observer, there is another behaviour of electromagnetic radiation, we call inertial radiation, which is characterized by an electromagnetic inertial density , and therefore, it happens to be described by a time-like Poynting four-vector field which propagates with velocity . is found to be a relativistic invariant expressible in terms of the relativistic invariants of the electromagnetic field. It is shown that there is a rest frame, where the Poynting vector is equal to zero. Both phase and group velocities of the electromagnetic radiation are evaluated. The wave and eikonal equations for the dynamics of the radiation field are formulated.

Density distribution in a heavy-medium cyclone

Heavy-medium cyclones are widely used to upgrade run-of-mine coal.But the understanding of flow in a cyclone containing a dense medium is still incomplete.By introducing turbulent diffusion into calculations of centrifugal settling a theoretical distribution function giving the density field can be deduced.Qualitative analysis of the density field in every part of a cylindrical cyclone suggests an optimum design that has exhibited good separation effectiveness and anti-wear performance when in commercial operation.

STUDIES ON MAGNETIC ABRASIVE MACHINING

This paper deals with the machining process using magnetic abrasives. Using an apparatus designed and made, a series of experiments are carried out, where the workpiece is cylindrical and the magnetic abrasives used are mainly Fe and Al 2O 3, for investigating the effects of machining time, working gap, rotating speed of workpieces, magnetic flux density on machining efficiency and surface roughness. At the end of this paper, the machining mechanism is also discussed.

Wind tunnel test on the effect of metal net fences on sand flux in a Gobi Desert, China

The Lanzhou-Xinjiang High-speed Railway runs through an expansive windy area in a Gobi Desert, and sand-blocking fences were built to protect the railway from destruction by wind-blown sand. However, the shielding effect of the sand-blocking fence is below the expectation. In this study, effects of metal net fences with porosities of 0.5 and 0.7 were tested in a wind tunnel to determine the effectiveness of the employed two kinds of fences in reducing wind velocity and restraining wind-blown sand. Specifically, the horizontal wind velocities and sediment flux densities above the gravel surface were measured under different free-stream wind velocities for the following conditions： no fence at all, single fence with a porosity of 0.5, single fence with a porosity of 0.7, double fences with a porosity of 0.5, and double fences with a porosity of 0.7. Experimental results showed that the horizontal wind velocity was more significantly decreased by the fence with a porosity of 0.5, especially for the double fences. The horizontal wind velocity decreased approximately 65% at a distance of 3.25 m（i.e., 13 H, where H denotes the fence height） downwind the double fences, and no reverse flow or vortex was observed on the leeward side. The sediment flux density decreased exponentially with height above the gravel surface downwind in all tested fences. The reduction percentage of total sediment flux density was higher for the fence with a porosity of 0.5 than for the fence with a porosity of 0.7, especially for the double fences. Furthermore, the decreasing percentage of total sediment flux density decreased with increasing free-stream wind velocity. The results suggest that compared with metal net fence with a porosity of 0.7, the metal net fence with a porosity of 0.5 is more effective for controlling wind-blown sand in the expansive windy area where the Lanzhou-Xinjiang High-speed Railway runs through.

2D-and 3D-QSBR Studies on the Relationship between Structure and Biodegradability of Phthalates

Nine phthalates were calculated at the B3LYP/6-311G＊＊ level using DFT method. The corresponding linear relationship equations （R2 were 0.853 and 0.936 respectively） for the biodegradation rate （Kb） and half-life time （h/2） of biodegradation were obtained with the structural parameters as theoretical descriptors. Furthermore, CoMFA method was also applied to establish 3D models which revealed the fields influencing these properties. The relationship between the properties and the structure was obtained. The correlation coefficients of the models were 0.992 and 0.999, respectively. Analyses of 2D and 3D models demonstrated that the molecular volume was an important factor affecting the biodegradability of these compounds.

THE OCCUPATION DENSITY FIELD FOR THE CATALYTIC SUPER-BROWNIAN MOTION

It is proved that the occupation time of the catalytic super-Brownian motion is absolutely continuous for d = 1, and the occupation density field is jointly continuous and jointly Holder continuous.

Effect of Drainage Ditch Layout on Nitrogen Loss by Runoff from an Agricultural Watershed

A comparison experiment was performed, by designing one field ditch （D1 treatment）, two field ditches （D2 treatment）, three field ditches （D3 treatment）, and no field ditch （CK treatment）, in an upland of a small agricultural watershed in Nanjing-Zhenjiang hilly regions to observe the farmland surface runoff and N loss characteristics under the different layouts of field ditch. As the layout density of field ditch increased, the drainage effect was improved, the timing of the runoff peak was advanced, and also the peak flow was augmented. At the same time, both the concentration and accumulated transfer flux of total nitrogen （TN） were improved, and thereinto the accumulated transfer fluxes of TN under D3, D2 and D1 treatments were increased by 1.46, 1.34 and 1.16 times, respectively, than that under CK treatment. However, the accumulated transfer fluxes of nitrate-nitrogen （NO3-N） and ammonium-nitrogen （NH4＋-N） under D3, D2 and D1 treatments were reduced by 33.9%, 21.4% and 8.6%, and 35.8%, 24.7% and 12.2%, respectively, compared with those under CK treatment. Under CK treatment, the NO3-N and NH4＋-N concentrations were more sensitive to rainfall intensity than the TN concentration. There were significant linear relationships between the transfer fluxes of TN, NO3-N and NH^-N and the runoff flux, with the correlation coefficients of 0.942, 0.899 and 0.912, respectively. In addition, this correlation was also influenced by the layout density of field ditch. Therefore, the environmental effect should be taken into account when designing and constructing field ditches. Especially in the regions of severe fertilizer loss, the approaches of properly increasing the drainage area and decreasing the layout density of field ditch could be adopted under the precondition of avoiding crops from waterlogging.

Investigation of adsorption behaviors of paraffin waxes on iron, iron oxide, and iron Ⅲ oxide pipeline's internal surfaces using adsorption locator model

Wax deposition in pipelines leads to pressure drop,reduced effective cross-sectional area,and blockages.Although mathematical models and experimental loops were used to model wax precipitation on pipeline surfaces,its prediction at molecular levels is not fully recognized.Molecular dynamics is another powerful approach that can predict wax precipitation at the molecular level.This paper uses molecular dynamics simulations with the adsorption locator model found in Material Studio Software to investigate the adsorption behaviors of Icosane-C20H42,Docosane-C22H46,and Tetracosane-C24H50 paraffin waxes on the Fe,FeO,and Fe2O3 pipeline internal surfaces.Modeling is performed by varying temperature values and validated with experimental data.It was found that as the temperature altered,the adsorption energies,probability energy distribution and adsorption density field on the surfaces also changed;on the other hand,the energetic analysis results showed adsorption energies increase with carbon numbers increase due to its larger surface contacting areas and lower aspect ratio,which resulted in stronger interaction with the surfaces.Further,paraffin waxes showed to adsorb easily on Fe surfaces than oxide surfaces.At temperatures below Wax Appearance Temperature(WAT)on both simulations and experiments showed wax deposition.The lower adsorption energy capacity observed on the Fe2O3 pipeline surface confirms it's vitality and suitability for crude oil transportation pipelines surface lining material.

Stability of Quark Star Models

In this paper,we investigate the stability of quark stars with four different types of inner matter configurations;isotropic,charged isotropic,anisotropic and charged anisotropic by using the concept of cracking.For this purpose,we have applied local density perturbations technique to the hydrostatic equilibrium equation as well as on physical parameters involved in the model.We conclude that quark stars become potentially unstable when inner matter configuration is changed and electromagnetic field is applied.