排序方式: 共有61条查询结果,搜索用时 234 毫秒
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Belcher Calvin H. Zheng Baolong MacDonald Benjamin E. Langlois Eric D. Lehman Benjamin Pearce Charles Delaney Robert Apelian Diran Lavernia Enrique J. Monson Todd C. 《Journal of Materials Science》2022,57(9):5518-5532
Journal of Materials Science - For transformers and inductors to meet the world’s growing demand for electrical power, more efficient soft magnetic materials with high saturation magnetic... 相似文献
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Reinhold Ludwig Sergey Makarov Diran Apelian 《Journal of Nondestructive Evaluation》1998,17(3):153-166
This paper investigates electrostatic voltage distributions around a surface-breaking flaw due to an injected current of known
strength. The direct 3-D solution of the voltage behavior over the flawed surface is obtained numerically by the use of a
boundary integral formulation. A novel iteration method is applied to solve the resulting electrostatic integral equation
for the unknown surface voltage distribution. In addition to investigating the sensitivity of different flaw sizes to the
observed surface voltage distribution, important issues such as suitable probe spacing and current flow orientation are studied.
For sufficiently small surface-breaking flaws, a simple image source model is developed to evaluate the voltage response of
hairline cracks. The model is tested by comparing it with the developed numerical solution. Experiments aimed at establishing
the validity of the modeling approach show remarkable agreement with the theoretical model. 相似文献
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Daniel Y. C. Wei Bakhtier Farouk Diran Apelian 《Metallurgical and Materials Transactions B》1988,19(1):213-226
A numerical model is developed for the prediction of melting metal powder particles in an inductively coupled r.f. plasma
torch. The model is developed for dilute spray conditions where the gas phase flow is not affected by the loading condition.
The governing equation for the gas phase flow contains the source terms from the electromagnetic field. The theoretical calculations
have shown that particle thermal history and its velocity are greatly affected by the plasma operating conditions (i.e., carrier gas flow rate, injector location, and power level,etc.). Without the proper control of particle trajectories, particles may bounce around the fireball and exit the torch as unmelted
or resolidified solid particles. With the insertion of an injector or injecting particles with a high carrier gas flow rate,
the predictions show that even relatively small size particles can be directed into the fireball and maintained in the molten
state before they impact on the substrate. Consequently, more uniform and dense deposits can be achieved. 相似文献
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A theoretical study was conducted using a multiple-voltage probe sensor for detecting nonconducting inclusions in conducting media. Results show that the multiple-voltage probe sensor is capable of providing precise quantitative measurements of submerged nonconducting objects if the surface voltage response has a standard two-peak form. The standard response is observed for well-localized non-slender single inclusions below the sensor surface. In this case, the peak separation distance is associated with the inclusion depth whereas the peak magnitude is associated with the inclusion volume. Linear dependencies of the inclusion depth and the inclusion volume are observed for a wide variety of inclusion shapes. The predefined form of the surface voltage response makes it feasible to identify useful signal responses at very high noise levels. This is accomplished by using a 2D neural network classifier, based on the probabilistic neural network. A reasonable recognition error of less than 20 % is obtained if the signal-to-noise ratio is larger than or equal to 1/10. A metal casting example shows that the multiple-voltage probe sensor can measure inclusion concentrations in hot conducting melts (gas bubbles and sludge) with inclusion radii in the range from 100 to 1000 m. In contrast to existing particle counter technology, this sensor construction is simple to construct and does not require special aperture and vacuum treatment. 相似文献
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Jung-Jen Allen Cheng Diran Apelian Roger D. Doherty 《Metallurgical and Materials Transactions A》1986,17(11):2049-2062
The rheocasting solidification process has been applied in the production of IN-100 nickel base superalloy. A high vacuum
furnace for rheocasting superalloys was used to rheocast ingots under different processing conditions. Processing variables
which were evaluated include stirring speed, isothermal stirring time, and volume fraction solid during isothermal stirring.
Ingots, furnace cooled at the same rate but without stirring, were also examined for comparison with the rheocast ingots.
A detailed microstructural examination was made of the resultant microstructure both on furnace cooling after stirring and
on reheating to the isothermal stirring temperature followed by water quenching. Rheocasting yielded fine-grained structures,
where the extent of microsegregatiori, the variation in macrostructure, and the solidification-induced porosity were found
to be reduced in comparison to the unstirred ingot. The grain size and nonuniformity in the as-cast ingot were reduced by
increasing the stirring speed, isothermal stirring time, or the volume fraction solid during stirring. The degree of the microsegregation
decreased significantly with increasing volume fraction solid. Grain boundaries, both with and without solute enrichment,
were found in the rosette-like solid particles after rheocasting, lending support to the Vogel-Cantor-Doherty model of rheocasting
based on the formation of grain boundaries by strain-induced recrystallization and by sintering. It is clear from these results
that the microstructure of this superalloy was significantly improved by rheocasting. Improved mechanical properties were
also found and will be reported separately. 相似文献