A piecewise continuous Timoshenko beam model for the dynamic analysis of tapered beam-like structures

Distributed parameter modeling offers a viable alternative to the finite element approach for modeling large flexible space structures. The introduction of the transfer matrix method into the continuum modeling process provides a very useful tool to facilitate the distributed parameter model applied to some more complex configurations. A uniform Timoshenko beam model for the estimation of the dynamic properties of beam-like structures has given comparable results. But many aeronautical and aerospace structures are comprised of non-uniform sections or sectional properties, such as aircraft wings and satellite antennas. This paper proposes a piecewise continuous Timoshenko beam model which is used for the dynamic analysis of tapered beam-like structures. A tapered beam is divided into several segments of uniform beam elements. Instead of arbitrarily assumed shape functions used in finite element analysis, the closed-form solution of the Timoshenko beam equation is used. Application of the transfer matrix method relates all the elements as a whole. By corresponding boundary conditions and compatible conditions a characteristic equation for the global tapered beam has been developed, from which natural frequencies can be derived. A computer simulation is shown in this paper, and compared with the results obtained from the finite element analysis. While piecewise continuous Timoshenko beam model decreases the number of elements significantly; comparable results to the finite element method are obtained

Adiabatic creation of coherent superposition states via multiple intermediate states

We consider an adiabatic population transfer process that resembles the well established stimulated Raman adiabatic passage (STIRAP). In our system, the states have nonzero angular momentums $J$, therefore, the coupling laser fields induce transitions among the magnetic sublevels of the states. In particular, we discuss the possibility of creating coherent superposition states in a system with coupling pattern $J=0\Leftrightarrow J=1$ and $J=1\Leftrightarrow J=2$. Initially, the system is in the J=0 state. We show that by two delayed, overlapping laser pulses it is possible to create any final superposition state of the magnetic sublevels $|2,-2>$, $|2,0>$, $|2,+2>$. Moreover, we find that the relative phases of the applied pulses influence not only the phases of the final superposition state but the probability amplitudes as well. We show that if we fix the shape and the time-delay between the pulses, the final state space can be entirely covered by varying the polarizations and relative phases of the two pulses. Performing numerical simulations we find that our transfer process is nearly adiabatic for the whole parameter set.Comment: 7 pages, 10 figure

Численное исследование зажигания смесевого топлива горячей частицей при неидеальном тепловом контакте

The mathematical model of the solid-phase condensed substance ignition by a metal particle heated to high temperatures in disk-shape was developed under the imperfect thermal contact conditions on the particle - composite propellant border, caused by a natural roughness of a composite propellant surface. The results of numerical research allowed to determine the ranges of energy source initial temperature and parameter characterizing a roughness of composite propellant surface at which radiative transfer in the field of a gas gap between a particle and solid propellant significantly (up to 25 %) influences values of the main integral characteristic of process - an ignition delay time

Optimization of molding parameter effect to warpage and shrinkage of laboratory goggle based on plastic flow simulation software

This thesis is about how to optimization of molding parameter effect to warpage and shrinkage. The product that will be use is laboratory goggle. The objective of this thesis is to analyze the parameters effect in injection molding to warpage and shrinkage of laboratory goggle and to determine the optimization of molding parameter effect to warpage and shrinkage of laboratory goggle during injection molding based on plastic flow simulation software. The thesis describes the moldflow software how to analyze frame and glass of laboratory goggle to identify the parameter effect to warpage and shrinkage of the product .. It need to scanning the frame and the glass of laboratory goggle and it need to use a 3D scanner machine. Then, transfer the shape and result to the solidwork software and find the dimension of the frame and glass to draw a new shape using solidwork software. Next, import the frame and glass from solidwork to the moldflow software and analyze the product. Make a optimization of the product from warpage and shrinkage. In this project, parameter in injection molding of laboratory goggle needs to define. The parameter includes mold temperature, melt temperature, injection time, and packing pressure. According to result from moldflow software, in conclusion the factor that influence the molding process it is pressure, temperature, molding temperature, molding cool must be in a correct position because it will be give a effect if the factor is not suitable

The role of photon scattering in shaping the lightcurves and spectra of gamma-ray bursts

We analyze the power spectra of the lightcurves of long gamma-ray bursts, dividing the sample in bins of luminosity, using the recently discovered variability-luminosity correlation. We find that the value of the variability parameter strongly correlates with the frequency that contains most of the power in the burst comoving frame. We compute the average power spectra in luminosity bins. The average power spectrum is well described by a broken power-low and the break frequency is a function of the variability parameter, while the two slopes are roughly constant. This allow us to conclude that scattering processes do not play a relevant role in modelling the lightcurves. We finally discuss in which conditions scattering may still play a relevant role in shaping the spectra of GRBs.Comment: Minor changes according to referee comments. Accepted for publication in MNRA

Shape-dependent Depinning of a Domain Wall by a Magnetic Field and a Spin-Polarized Current

The effect of sample shape on the depinning of the domain wall (DW) driven by an applied magnetic field or a spin-polarized current is studied theoretically. The shape effect resulting from the modulation of the sample width (geometric pinning) can essentially affect the DW depinning. We found a good agreement between the ratios of the critical values of the magnetic field and the spin-polarized current predicted by the theory and measured in the experiment.Comment: 9 pages, 5 figure

Microwave-controlled generation of shaped single photons in circuit quantum electrodynamics

Large-scale quantum information processors or quantum communication networks will require reliable exchange of information between spatially separated nodes. The links connecting these nodes can be established using traveling photons that need to be absorbed at the receiving node with high efficiency. This is achievable by shaping the temporal profile of the photons and absorbing them at the receiver by time reversing the emission process. Here, we demonstrate a scheme for creating shaped microwave photons using a superconducting transmon-type three-level system coupled to a transmission line resonator. In a second-order process induced by a modulated microwave drive, we controllably transfer a single excitation from the third level of the transmon to the resonator and shape the emitted photon. We reconstruct the density matrices of the created single-photon states and show that the photons are antibunched. We also create multipeaked photons with a controlled amplitude and phase. In contrast to similar existing schemes, the one we present here is based solely on microwave drives, enabling operation with fixed frequency transmons