Музыкальный информационный поиск с запросом по напеву

In this paper the problems of Query by Humming in Music Information Retrieval systems are analyzed. A statistical approach to the problem of retrieval is presented. The processes of segmentation as well as of the extraction of pitch and duration data are described. From the extracted data the characteristic vector is formed for each segment. The method of using the vectors in melodic search if proposed

Modulated Martensite: Why it forms and why it deforms easily

Diffusionless phase transitions are at the core of the multifunctionality of (magnetic) shape memory alloys, ferroelectrics and multiferroics. Giant strain effects under external fields are obtained in low symmetric modulated martensitic phases. We outline the origin of modulated phases, their connection with tetragonal martensite and consequences for their functional properties by analysing the martensitic microstructure of epitaxial Ni-Mn-Ga films from the atomic to macroscale. Geometrical constraints at an austenite-martensite phase boundary act down to the atomic scale. Hence a martensitic microstructure of nanotwinned tetragonal martensite can form. Coarsening of twin variants can reduce twin boundary energy, a process we could follow from the atomic to the millimetre scale. Coarsening is a fractal process, proceeding in discrete steps by doubling twin periodicity. The collective defect energy results in a substantial hysteresis, which allows retaining modulated martensite as a metastable phase at room temperature. In this metastable state elastic energy is released by the formation of a 'twins within twins' microstructure which can be observed from the nanometre to millimetre scale. This hierarchical twinning results in mesoscopic twin boundaries which are diffuse, in contrast to the common atomically sharp twin boundaries of tetragonal martensite. We suggest that observed extraordinarily high mobility of such mesoscopic twin boundaries originates from their diffuse nature which renders pinning by atomistic point defects ineffective.Comment: 34 pages, 8 figure

Modeling magnetoelasticity and magnetoplasticity with disconnections and disclinations

The magneto mechanical properties of magnetic shape memory alloy single crystals depend strongly on the twin microstructure which is established during the martensitic transformation, and through thermo magneto mechanical training. For self accommodated martensite, twin thickness and magnetic field induced strain are very small. For effectively trained crystals, a single twin may comprise the entire sample and magnetic field induced strain reaches the theoretical limit. Furthermore, the deformation of self accommodated martensite is pseudoelastic magnetoelasticity while the deformation of effectively trained crystals is plastic magnetoplasticity . Twin microstructures of self accommodated martensite were modeled using disclinations which are line defects such as dislocations, however with a rotational displacement field. The defect structure was approximated in a quadrupole solution where two quadrupoles represent an elementary twin double layer unit. The twin boundary was inclined to the twinning plane which required the introduction of twinning disconnections. The shear stress shear strain properties of self accommodated martensite were analyzed numerically for different initial configurations of the twin boundary i.e. for different initial positions of the disconnections . The shear stress shear strain curve is sensitive to the initial configuration indicating that disconnection nucleation is controlling the magneto mechanical properties of self accommodated martensit

Effect of Porosity on the Magneto-Mechanical Behavior of Polycrystalline Magnetic Shape-Memory Ni–Mn–Ga Foams

Porosity in polycrystalline Ni–Mn–Ga alloys reduces internal constraints imposed by grain boundaries which suppress magnetic-field-induced strain in non-porous, polycrystalline magnetic shape-memory alloys. We present here a systematic study of the porosity effect on the magneto-mechanical properties of polycrystalline Ni–Mn–Ga foams. Starting from replicated foams created by casting with ceramic space holders, their porosities were increased by successive acid dissolution steps after which the magnetic-field-induced strain was measured, for each porosity level, after thermo-magneto-mechanical training. Consistently, the magnetic-field-induced strain increased with increasing porosity, in the extreme case by one order of magnitude for a small porosity increase of 1.3%, demonstrating that removal of constraints by porosity is responsible for the high magnetic-field-induced strain in polycrystalline Ni–Mn–Ga foams

Magnetic, Mechanical and Fatigue Properties of a Ni\u3csub\u3e45.4\u3c/sub\u3eMn\u3csub\u3e29.1\u3c/sub\u3eGa\u3csub\u3e21.6\u3c/sub\u3eFe\u3csub\u3e3.9\u3c/sub\u3e Single Crystal

In this work the magnetic, mechanical and fatigue behaviour of a Ni45.4Mn29.1Ga21.6Fe single crystal are reported. The crystal shows a martensite temperature (TM) of 50 °C. A mechanically induced strain of 6% could be detected. The Ni–Mn–Ga–Fe alloy exhibited a magnetic field-induced strain (MFIS) of 4% in a magnetic field of 400 mT. After more than 60,000 magneto-mechanical cycles in a constant magnetic field of 1 T a MFIS of 4.5% was measured

Grain growth, porosity, and hardness changes in sintered and annealed binder jet 3D printed Ni Mn Ga magnetic shape memory alloys

In this study, neutron diffraction was performed on binder jet printed Ni Mn Ga alloys which were sintered at different temperatures. The data from these measurements show a large difference in Bragg diffraction peaks due to grain size difference sintered at 1080 C and 1090 C as revealed by the images obtained by the area detector and grain boundaries revealed during etching. Also, the decrease in porosity with increasing sintering temperature resulted in an increase in hardnes

Magneto Mechanical Properties and Fracture of a Mechanically Constrained Ni Mn Ga Single Crystal after Extended Magnetic Cycling

In a previous study, magnetic field induced strain MFIS had been measured for a Ni Mn Ga single crystal in a rotating magnetic field of 0.97 T for a total of 100 million cycles. The MFIS increased from below 0.5 during the first 20,000 magneto mechanical cycles to above 1.2 at 250,000 cycles. After a maximum MFIS of 2.1 at 0.6 million cycles was reached, the MFIS decreased slowly and stayed nearly constant for the final 30 million cycles. After the test was stopped, cracks were found on the surface of the sample. In the present work, these cracks were examined using x ray micro computer tomography and optical microscopy. The magneto mechanical properties of the sample were then tested in a static magneto mechanical experiment with linear magnetic field showing a recoverable strain increasing from less than 1 at 0.3 T to 5.9 at 1 T. Subsequently, the sample was forcibly broken. The parts of the fracture surfaces cracked forcibly show plastic deformation while the cracks grown slowly during magneto mechanical cycling follow crystallographic planes. The results confirm that cracks nucleate where coarse twins interact, while densely twinned microstructures are fracture resistan