1,510 research outputs found
On subgroups in division rings of type
Let be a division ring with center . We say that is a {\em
division ring of type } if for every two elements the division
subring is a finite dimensional vector space over . In this paper
we investigate multiplicative subgroups in such a ring.Comment: 10 pages, 0 figure
Ultrasonic Assisted Deep Drilling of Inconel 738LC Superalloy
AbstractSuperalloys have a poor machinability and are often drilled using Electro Discharge Machining (EDM) methods. However EDM is a time-consuming process and has low surface integrity. Ultrasonic Assisted Drilling (UAD) technology is a modern method of drilling such materials. Although this method has very high capabilities, it has not been introduced widely to industry. In this study a special horn is designed and used to apply both rotation and vibration to drill bits. It can transfer power with high efficiency and has the capability to change tools easily. The setup is used to conduct deep drilling tests on Inconel 738LC with depth-to-diameter ratio of 10. The effect of ultrasonic vibration amplitude, spindle speed and number of steps to drill each hole on machining force and surface roughness were investigated. Optimized conditions and results predicted by Taguchi method showed close agreement with the results obtained by experiments
Remarkable paramagnetic features of Fermi-Dirac plasmas
In this paper by using the relativistic magnetic susceptibility of a
Fermi-Dirac (relativistically degenerate) plasma, quantum magnetohydrodynamics
(QMHD) model is used to investigate the propagation of spin-induced (SI)
magnetosonic nonlinear excitations in a normally and relativistically
degenerate dense electron-ion plasma in the presence of the spin magnetization
effect. Based on the conventional pseudopotential method the matching criterion
for the evolution of SI solitary structures is evaluated. It is found that, the
plasma mass density and strength of the magnetic field have significant effects
on excitation and evolution of magnetosonic nonlinear structures in Fermi-Dirac
plasmas. Only rarefactive SI magnetosonic solitary structures are found to
excite in such plasmas. Furthermore, fundamental differences are shown to exist
in magnetosonic soliton dynamics in the two distinct plasma degeneracy regimes,
which is due to interplay between the negative spin paramagnetism pressure-like
and positive relativistic degeneracy pressure of electrons. Current
investigation can help better understand the electron spin effects on nonlinear
wave propagations in strongly magnetized dense astrophysical objects such as
white dwarfs and pulsar magnetospheres.Comment: To be published in Journal Physics of Plasma
Nanobiosensor designing with molecular framework polymer method compared with agent-linked nanosilica biosensor for Staphylococcus aureus exotoxin detection
Considering the ever increasing population and industrialization leading to developmental trend of humankind's life, we are hardly able to detect the toxins produced in food products using traditional techniques. In this technique, the production of molecular framework and polymer is done using meta acrylic acid monomers, which are formed via covalence connection between meta acrylic acid monomers (MAA) of white polymer. Here also hydrogenised connection between exotoxin amino acid and meta acrylic acid is made that would function as the selective absorption for that. Then in the second stage, based on the bacterial antibody connection to nanoparticle, a sensor was used. In this part of the research, as the basis for absorption for the recognition of bacterial toxin, medium sized silica nanoparticles of 10 nanometer in the form of solid powder were utilized with Notrino brand. Then the suspension produced from agent-linked nanosilica which was connected to bacterial antibody was positioned near the samples of distilled water, that were contaminated with Staphylococcus aureus bacterial toxin with the density of 10^-3, so that in case any toxin exists in the sample, a connection between toxin antigen and antibody would be formed. Finally, the light absorption related to the connection of antigen to the particle attached antibody was measured using spectrophotometers. The results indicate that the molecular framework polymer sensor is capable of detecting up to the density of 10^-3, but not lower than that, whereas using the second sensor, up to 10^-4 of density is detectable. Additionally, the sensitivity of the sensors were examined after 60 days and the first sensor by the day of 28 and the second sensor by the 56 day had confirmatory results and started to decrease after those time periods
Adsorption of Arsenic from Aqueous Solutions by Iron Filings and the Effect of Magnetic Field
Aims: Arsenic contamination of natural water resources has become an important environmental problem in the world. The adsorption method by iron filings adsorbent or zero-valent iron was used. The study aimed to evaluate the efficiency of iron filings in arsenite removal from polluted water and to investigate the effect of magnetic field on the process. Materials & Methods: This interventional study was conducted in synthetically polluted water samples with certain arsenic concentrations. With regard to the initial arsenic concentration (0.5 and 2mg/l), iron filings dosages (0, 2.5 and 5g/l), contact times (5, 10 and 15min) and considering the samples before and after magnetic column, 108 samples were prepared. Data was analyzed by paired sample T and one-way ANOVA tests. Findings: The highest mean of removal efficiency at the initial arsenic concentration of 0.5mg/l was seen at the iron filings of 5g/l and 10min contact time (87.7±10.0) and at the initial arsenic concentration of 2mg/l was seen at the iron filings of 5g/l and 15min contact time (86.3±8.4). At the initial arsenic concentration of 0.5mg/l, magnetic field increased the removal efficiency of arsenite at the iron filings dosage of 0g/l and decreased it at the iron filings dosage of 5g/l. The same happened at the initial arsenic concentration of 2mg/l. Conclusion: Arsenic is reduced from the water samples with the iron filings dosage of 5g/l at natural pH. Magnetic field increases the arsenic removal efficiency in the absence of the iron filings and decreases the arsenic removal efficiency in the presence of the iron filings
Orbital Ferromagnetism and Quantum Collapse in Stellar Plasmas
The possibility of quantum collapse and characteristics of nonlinear
localized excitations is examined in dense stars with Landau orbital
ferromagnetism in the framework of conventional quantum magnetohydrodynamics
(QMHD) model including Bohm force and spin-orbit polarization effects.
Employing the concepts of effective potential and Sagdeev pseudopotential, it
is confirmed that the quantum collapse and Landau orbital ferromagnetism
concepts are consistent with the magnetic field and mass-density range present
in some white dwarf stars. Furthermore, the value of ferromagnetic-field found
in this work is about the same order of magnitude as the values calculated
earlier. It is revealed that the magnetosonic nonlinear propagations can behave
much differently in the two distinct non-relativistic and relativistic
degeneracy regimes in a ferromagnetic dense astrophysical object. Current
findings should help to understand the origin of the most important mechanisms
such as gravitational collapse and the high magnetic field present in many
compact stars.Comment: To appear in journal Physics of Plasma
Spectra of strongly Deza graphs
A Deza graph with parameters is a -regular graph with
vertices such that any two distinct vertices have or common neighbours.
The children and of a Deza graph are defined on the vertex set
of such that every two distinct vertices are adjacent in or if
and only if they have or common neighbours, respectively. A strongly
Deza graph is a Deza graph with strongly regular children. In this paper we
give a spectral characterisation of strongly Deza graphs, show relationships
between eigenvalues, and study strongly Deza graphs which are distance-regular
Effect of rare earth dopants on structural and mechanical properties of nanoceria synthesized by combustion method
Structural characteristics of combustion synthesized, calcined and densified pure and doped nanoceria with tri-valent cations of Er, Y, Gd, Sm and Nd were analyzed by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The results showed that the as-synthesized and calcined nanopowders were mesoporous and calculated lattice parameters were close to theoretical ion-packing model. The effect of dopants on elastic modulus, microhardness and fracture toughness of sintered pure and doped ceria were investigated. It was observed that tri-valent cation dopants increased the hardness of the ceria, whereas the fracture toughness and elastic modulus were decreased
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