Analisis Perencanaan Jarak Celah Udara Pada Generator Axial

The generator uses a permanent magnet so it does not require initial excitation to generate a voltage. The generator design is axial flux type, uses ceramic type permanent magnet (NdFeB), uses two flanking stator rotors. For electricity use, the AC voltage is changed to DC voltage using a rectifier for charging the accumulator. The air gap in the axial generator is the distance between the rotor and the stator. The air gap is also a place for the transfer of the magnetic field through the coil on the stator to produce a magnetic flux value that affects the induced voltage in the coil. The faster the rotation, the greater the voltage generated. This axial generator that has been designed can produce a frequency of ± 50 Hz, an effective voltage of ± 22 V when the air gap is 2 mm, the frequency measurement has an error of 10-20 Hz and an error percentage of 5-10%, with the results of measuring the induced current that has a large the same voltage.

Rail Corrugation of High-Speed Railway Induced by Rail Grinding

Rail corrugation is a common railway defect that involves diverse and complex factors. Rail grinding is also the most commonly used method to address corrugations. Through numerous irregularity tests and one-third octave frequency spectrum analyses, this study determined the characteristics and development process for rail corrugation on high-speed rail tracks. The vibration transmission properties of the grinding train were tested using the force hammer impacting method. Thereafter, using a simulation, the influence of the vertical vibration behavior of the grinding stone and the stiffness of the hydraulics were determined. Through a series of field tests and numerical simulations, this study revealed a clear correlation between rail corrugation and rail grinding and confirmed that the technical operation of rail grinding is closely associated with regular grinding marks at a wavelength of approximately 60 mm on rail surfaces. The combination of the natural vibration of the grinding stone (frequency of 60 Hz) and an inappropriate operational process can aggravate the grinding marks on the rail surfaces, thereby forming an initial excitation of rail corrugation. Although a large number of irregularity tests are performed after rail grinding, these wavelength-fixing grinding marks can cause the formation and development of rail corrugation. Suggestions for improving the high-speed rail-grinding technology are also provided.

Deformation Parameters and Collective Temperature Changes in Photofission Mass Yields of Actinides Within the Systematic Statistical Scission Point Model

The photofission fragment mass yields of actinides are evaluated using a systematic statistical scission point model. In this model, all energies at the scission point are presented as a linear function of the mass numbers of fission fragments. The mass yields are calculated with a new approximated relative probability for each complementary fragment. The agreement with the experimental data is quite good, especially with a collective temperature Tcol of 2 MeV at intermediate excitation energy and Tcol = 1 MeV for spontaneous fission. This indicates that the collective temperature is greater than the value obtained by the initial excitation energy. The generalized superfluid model is applied for calculating the fragment temperature. The deformation parameters of fission fragments have been obtained by fitting the calculated results with the experimental values. This indicates that the deformation parameters decrease with increasing excitation energy. Also, these parameters decrease for fissioning systems with odd mass numbers.

Energy sharing based on microscopic level densities

The transformation of a moderately excited heavy nucleus into two excited fission fragments is modeled as a strongly damped evolution of the nuclear shape. The resulting Brownian motion in the multi-dimensional deformation space is guided by the shape-dependent level density which has been calculated microscopically for each of nearly ten million shapes (given in the three-quadratic-surfaces parametrization) by using a previously developed combinatorial method that employs the same single-particle levels as those used for the calculation of the pairing and shell contributions to the five-dimensional macroscopic-microscopic potential-energy surface. The stochastic shape evolution is followed until a small critical neck radius is reached, at which point the mass, charge, and shape of the two proto-fragments are extracted. The available excitation energy is divided statistically on the basis of the microscopic level densities associated with the two distorted fragments. Specific fragment structure features may cause the distribution of the energy disvision to deviate significantly from expectations based on a Fermi-gas level density. After their formation at scission, the initially distorted fragments are being accelerated by their mutual Coulomb repulsion as their shapes relax to their equilibrium forms. The associated distortion energy is converted to additional excitation energy in the fully accelerated fragments. These subsequently undergo sequential neutron evaporation which is calculated using again the appropriate microscopic level densities. The resulting dependence of the mean neutron multiplicity on the fragment mass, as well as the dependence of on the initial excitation energy of the fissioning compound nucleus, exhibit features that are similar to the experimentally observed behavior, suggesting that the microscopic energy sharing mechanism plays an important role in low-energy fission.

Substitution pattern dependent behavior of the singlet excited states in symmetrically fluorinated biphenyls

We report stationary and ultrafast solution-phase spectra for symmetric biphenyls: pristine biphenyl (bP0), 4,4'-difluorobiphenyl (bP2), 2,3,5,6,2',3',5',6'-octafluorobiphenyl (bP8), and perfluorobiphenyl (bP10). Initial excitation to the S3 state in bP0 and bP2,...

Planar vibrations of rigid structure on kinematic supports after A.M. Kurzanov

The author carries out parametric studies for the equation of planar vibrations of rigid structure resting on kinematical rolling supports with planar bottom (after A.M. Kurzanov). Both support and the surface below are assumed rigid; no sliding assumed. Varied parameter is the width of the bottom. Horizontal structural acceleration is studied. Three variants of the possible behavior are shown: (i) minor rocking with little decrease in response accelerations as compared to the initial excitation; considerable rocking with considerable decrease in the response accelerations; intensive rocking leading to the overturn of the supports. In vertical direction there appear shocks (infinite accelerations) during gap closings of the supports. The importance of the problem for the seismic response analysis of the unanchored items is noted. The author gives recommendations for the experimental program, aimed to obtain data about damping both for rotation and for the gap closing, and also about the impact of the flexibility of the supports and underlying surface.