共查询到20条相似文献,搜索用时 31 毫秒
1.
Yamada K Kasai S Nakatani Y Kobayashi K Kohno H Thiaville A Ono T 《Nature materials》2007,6(4):269-263
A magnetic vortex is a curling magnetic structure realized in a ferromagnetic disk, which is a promising candidate for a memory cell for future non-volatile data-storage devices. Thus, an understanding of the stability and dynamical behaviour of the magnetic vortex is a major requirement for developing magnetic data-storage technology. Since the publication of experimental proof for the existence of a nanometre-scale core with out-of-plane magnetization in a magnetic vortex, the dynamics of vortices have been investigated intensively. However, a way to electrically control the core magnetization, which is a key for constructing a vortex-core memory, has been lacking. Here, we demonstrate the electrical switching of the core magnetization by using the current-driven resonant dynamics of the vortex; the core switching is triggered by a strong dynamic field that is produced locally by a rotational core motion at a high speed of several hundred metres per second. Efficient switching of the vortex core without magnetic-field application is achieved owing to resonance. This opens up the potentiality of a simple magnetic disk as a building block for spintronic devices such as a memory cell where the bit data is stored as the direction of the nanometre-scale core magnetization. 相似文献
2.
One way of testing color vision is with a color-blindness plate (CBP) consisting of a set of brilliant colored dots to form a pattern (a figure) and a set of other colored dots to form a background. Classification of such a type of color image into a pattern and a background with a traditional technique is difficult. Based on a self-organizing feature map and a labeling process as well as spatial distance computation, an effective approach to the segmentation of a CBP image is presented. We describe the principle of a CBP segmentation and then introduce the CBP. The proposed approach is described, and its experimental results are presented. We conclude that the method can segment the CBP image into a pattern and a background successfully. 相似文献
3.
G. V. Dedkov 《Technical Physics Letters》2004,30(8):693-696
The effect of a thin adsorbed film on the fluctuational electromagnetic tangential force of interaction between a moving nanoparticle
and a flat solid surface was theoretically studied for the first time in a nonrelativistic approximation. Particular calculations
were performed for a metal film on a dielectric and for a dielectric film on a metal. In both cases, the nanoparticle is assumed
to be made of a nonmagnetic metal. It is shown that, at a normal temperature, the presence of an adsorbed film may lead to
an increase in the tangential friction force by one or two orders of magnitude for a certain relation between the particle
distance from the surface and the film thickness. In the case of a dielectric film on a metal substrate, a decrease in the
temperature is accompanied by exponential decrease in the viscous friction. For a metal film on a dielectric substrate, the
tangential force exhibits a quadratic dependence on the temperature. 相似文献
4.
Shun Takai 《Research in Engineering Design》2009,20(4):255-264
It is generally acknowledged that product development involves a sequence of decision making under uncertainty, including
setting target requirements for a new product, selecting product concept, and developing conceptual and detailed design of
a chosen concept. To select a product concept, engineers need to assess the uncertainty of a future market share, market size,
and a cost of concept (cost of the final product developed from a concept). This paper proposes a case-based reasoning (CBR)
approach to model beliefs about the uncertainty of a cost of concept. The proposed CBR approach consists of storing information
about various products in a knowledge-base, defining a new product concept, retrieving a cluster of products in the knowledge-base
that are highly similar to the concept, and adapting the cost of the retrieved product to construct a distribution of the
cost of concept. This paper illustrates the proposed approach using printers as an example. 相似文献
5.
N. I. Plyusnin 《Technical Physics Letters》2018,44(11):980-983
Based on the data on the atomic density of a film and degree of its homogeneity during the formation of the interface between 3d transition metals (Cr, Co, Fe, or Cu) and silicon, a new concept of forming a contact between a reactive metal and a semiconductor has been justified. According to this concept, the low-temperature vapor-phase deposition of a metal onto a semiconductor is accompanied by the formation of a two-dimensional nanophase wetting layer of a metal or its mixture with silicon with a thickness of several monolayers, which significantly affects the interface formation and structure. This concept changes a perspective of forming a contact between a metal and a semiconductor substrate: it is necessary to take into account not only the formation of surface phases and clusters and/or the mixing process, but also the effect of elastic wetting of a substrate by the forming phases. 相似文献
6.
The variational form of a mathematical model of a thermal explosion has been developed based on a variational formulation of a nonlinear problem of stationary thermal conductivity in a homogeneous solid body. The model takes the temperature dependence of the thermal conductivity of a solid body into account. The presented example of quantitative analysis of the model demonstrates a method for finding the combination of parameters for determining a thermal explosion in a plate with an exponential temperature dependence of the thermal conductivity. At the same time, the analysis allows one to identify the number of steadystate temperature distributions inside a body whose energy release intensifies with a temperature increase. 相似文献
7.
Andrew Lahy Ai Qiang Li Pauline Found Aris Syntetos Mike Wilson Nicole Ayiomamitou 《国际生产研究杂志》2018,56(6):2233-2249
A Product–Service System (PSS) is created by combing a tangible product and an intangible service into one integrated offering. Thus, a PSS can be achieved by a production company adding intangible services to a product using a servitisation strategy or by a service company adding a tangible product to a service by means of a productisation strategy. The focus of this paper is on the latter. Our work demonstrates a significant gap in the literature in this area. To address this, we adapt an existing PSS conceptual framework as a means to identify the driving and restraining forces considered by a service company as it explored the possibility of pursuing a PSS productisation strategy. The conceptual framework is applied in an exploratory case study with a 3PL service provider. Application of the framework reveals new driving and restraining forces not previously discussed in the literature. Furthermore, it allows a preliminary quantification of the driving and restraining forces using a force field analysis approach. Our work contributes towards the expansion of the empirical knowledge base in the area of PSS. 相似文献
8.
B. S. Mogilnitskii 《Measurement Techniques》2009,52(12):1263-1270
An analysis of the spectral-time characteristics of a Fabry–Perot interferometer (FPI) in pulsed illumination is given. Processes
that occur in the transit of light pulses of different widths through a FPI are considered in detail. A relationship between
the baseline of a FPI and the width of the incident light pulse is established. The time structure of a pulse that has traversed
a FPI is analyzed. The theoretical difference in the transit of a light pulse through a FPI and of a regular sequence of synchronized
laser pulses is found. The maximum time resolution of a FPI is determined. A model that describes the transit of a regular
sequence of synchronized laser pulses through a FPI functioning in the mode of an optical filter is determined. 相似文献
9.
10.
The properties of a laser beam coupled out of a standard unstable laser resonator are heavily dependent on the chosen resonator magnification. A higher magnification results in a higher output coupling and a better beam quality. But in some configurations, an unstable resonator with a low output coupling in combination with a good beam quality is desirable. In order to reduce the output coupling for a particular resonator, magnification fractions of the outcoupled radiation are reflected back into the cavity. In the confocal case, the output mirror consists of a spherical inner section with a high reflectivity and a flat outer section with a partial reflectivity coating. With the application of the unstable resonator with reduced output coupling (URROC), magnification and output coupling can be adjusted independently from each other and it is possible to get a good beam quality and a high power extraction for lasers with a large low gain medium. The feasibility of this resonator design is examined numerically and experimentally with the help of a chemical oxygen iodine laser. 相似文献
11.
Based on the results of electromagnetic simulations for a dielectric structure comprising a grating over a homogeneous layer,
a new magnetooptical effect is predicted according to which the phase of the transmitted zeroth order of diffraction must
exhibit resonant variation during a change in the magnetization of the material. The structure is magnetized in the plane
of the grating, in a direction perpendicular to its grooves. Since the magnitude of this effect is greater by several orders
than that of the analogous effect for a homogeneous magnetized layer, the new effect is called extraordinary. The phenomenon
is given a theoretical explanation based on a resonance excitation of an eigenmodes in the structure and the dependence of
the mode frequency on the magnetization. It is shown that a large change in the phase of the transmitted order of diffraction
is achieved at a certain ratio of the resonant and nonresonant diffraction processes. 相似文献
12.
In this study, a new method for calculating the dynamic stress intensity factors of a bimaterial bending specimen with an interface crack is proposed by making use of a line-spring model. A pre-cracked bending specimen is modeled by one-dimensional beam finite elements and a line-spring representing the stiffness or compliance of a cracked part. The proposed method enables the one-dimensional analysis of a two-dimensional crack problem; thus the time variations of the dynamic stress intensity factors of a bimaterial bending specimen with an interface crack can be obtained by making use of a personal computer within a few minutes. The results obtained by the proposed method agree reasonably well with those obtained by the two-dimensional finite element method, although a slight difference in period can be found. The proposed method enables rapid evaluation of dynamic stress intensity factors. So a rapid evaluation system of the dynamic fracture toughness of a bimaterial with an interface crack can be achieved by combining an instrumented impact test apparatus with a computer program based on the proposed method which runs on a personal computer. 相似文献
13.
A formula is given for a more accurate estimate of either the resistivity and permeability of a cylindrical magnetic material or the resistivity and penetration depth of a cylindrical superconductor, using the difference in the complex impedance between a circular multilayer solenoid coil having a conductor and a similar coil without a conductor. In comparison with the conventional method which uses a single-layer solenoid coil, it is shown experimentally that a multilayer solenoid coil is more effective for a short sample conductor because a larger difference in the complex impedance is obtained without increasing the width of the solenoid coil. The results of measurements of magnetic and superconductive materials are included 相似文献
14.
15.
Oh MS Kong HJ Kim TH Jo SE Kim BW Park DJ 《Journal of the Optical Society of America. A, Optics, image science, and vision》2011,28(5):759-765
In this paper, a photon-counting three-dimensional imaging laser detection and ranging (LADAR) system that uses a Geiger-mode avalanche photodiode (GAPD) of relatively short dead time (45 ns) is described. A passively Q-switched microchip laser is used as a laser source and a compact peripheral component interconnect system, which includes a time-to-digital converter (TDC), is set up for fast signal processing. The combination of a GAPD with short dead time and a TDC with a multistop function enables the system to operate in a single-hit or a multihit mode during the acquisition of time-of-flight data. The software for the three-dimensional visualization and an algorithm for the removal of noise are developed. For the photon-counting LADAR system, we establish a theoretical model of target-detection and false-alarm probabilities in both the single-hit and multihit modes with a Poisson statistic; this model provides the prediction of the performance of the system and a technique for the acquisition of a noise image with a GAPD. Both the noise image and the three-dimensional image of a scene acquired by the photon-counting LADAR system during the day are presented. 相似文献
16.
This paper describes a reusable platform that can apply a linear temperature gradient to a lab-on-a-chip device. When a planar microfluidic device with a series of microchannels is placed on top of the platform with the channels perpendicular to the gradient, each channel is held at a discrete temperature. This allows temperature-dependent data for chemical or biochemical species flowed into the device to be obtained in a concurrent fashion. As a demonstration, a melting curve for dsDNA is performed by collecting all the data simultaneously. The gradient is stable enough to easily distinguish between 30-mers where the complement strand contains a single C-A mismatch or a single T-G mismatch or is a perfect match. On the other hand, a temperature gradient can be formed parallel to the direction of flow of the microchannels. This allows the temperature in each channel to vary continuously as the liquid flows downstream. If each microchannel in the array contains a distinct pH value, ionic strength, species concentration, or chemical composition, then a high-throughput two-variable experiment can be performed. We demonstrate this mode of data collection by measuring the fluorescence yield of fluorescein dye molecules in aqueous solution simultaneously as a function of concentration and temperature. 相似文献
17.
Fordy AP 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2011,369(1939):1264-1279
We consider a class of map, recently derived in the context of cluster mutation. In this paper, we start with a brief review of the quiver context, but then move onto a discussion of a related Poisson bracket, along with the Poisson algebra of a special family of functions associated with these maps. A bi-Hamiltonian structure is derived and used to construct a sequence of Poisson-commuting functions and hence show complete integrability. Canonical coordinates are derived, with the map now being a canonical transformation with a sequence of commuting invariant functions. Compatibility of a pair of these functions gives rise to Liouville's equation and the map plays the role of a B?cklund transformation. 相似文献
18.
19.
The main results obtained when studying a temperature dependence of the uniaxial anisotropy of oblique-incidence magnetic films of cobalt are given. It has been stated that when depositing the films onto a substratum heated to 350°C, the easy magnetization axis (EA) is perpendicular to the incidence plane of a molecular beam (a positive anisotropy). EA is in the incidence plane (a negative anisotropy) when the temperature of a substratum is 60 to 80°C. At intermediate temperatures of a substratum a positive anisotropy arises at small angles of deposition and a negative one is at great angles of deposition. Temperature dependences of the constant of the uniaxial anisotropy for samples with a positive or negative anisotropy distinguish between each other. In samples with a positive anisotropy this constant changes with the temperature as a square of magnetization; in samples with a negative anisotropy at less than room temperatures, this constant is approximately proportional to the anisotropy constant of a massive-cobalt single crystal. The obtained results have been considered from the theoretical point of view, and it has been concluded that a negative anisotropy in oblique-incidence films arises as a result of formation of very small grains stretching in the direction of the incidence plane and having a significant anisotropy of the magnetic energy in layers adjoining the boundaries (the Néel anisotropy). Observation of the typical temperature dependence of the anisotropy constant of these samples is a very convincing proof of existence of the Néel anisotropy. 相似文献
20.
A filter for on-line estimation of spectral content 总被引:1,自引:0,他引:1
Mallory G.J.W. Doraiswami R. 《IEEE transactions on instrumentation and measurement》1999,48(6):1047-1055
A robust filter algorithm to extract, a posteriori, the rational signal model from a noisy measurement, with little a priori information, is proposed. The spectrum and the statistics of the signal and of the corrupting noise are assumed unknown, except that the signal is assumed to have a rational spectrum. An algorithm based on system and signal theory is derived to select a set of frequencies where the signal-to-noise ratio (SNR) is high from a given measurement spectrum. The density of selected frequencies weights the importance of the measurement as a function of frequency, An estimate of the signal model is obtained from the best weighted least-squares fit to the measurement spectrum at the selected frequencies. The proposed filter has applications to control and signal processing, and a wide variety of applications are presented. Applications include: system identification of a dc motor and a two-link manipulator, extraction of a myo-electric signal from a noisy measurement, the assignment of a rational model to a vegetation tissue's impedance, and to the number density profile of atmospheric oxygen 相似文献