Multiwavelength, multilevel optical storage using dielectricmirrors

Optical storage systems store information at densities higher than other technologies and are less expensive per byte. Optical disk storage has been touted as a replacement for magnetic disks, but suffers from longer access times and lower data rates. The lower data rate of optical disks is partially due to lower disk rotation rates, but mainly a result of reading optical disks individually, rather than in parallel like magnetic disks. Reading several optical disks in parallel is possible but may complicate the removability of the disks. In this letter, we describe a wavelength-selective, multilayer disk based on dielectric mirrors that has potential to achieve a high degree of integration and parallelism     

Capacitance of Coupled Circular Microstrip Disks

The coupling between circular disks placed on a grounded dielectric substrate is studied analytically and numerically. The problem is formulated exactly by applying the Kobayashi potential, which uses discontinuity properties of Weber-Schafheitlin integrals, as an electrostatic problem when the potentials on the disks are specified. Numerical results for charge distribution and gap capacitance are presented. The potential distribution on the disks is calculated numerically to check if it satisfies the specified boundary condition.     

Radiation characteristics of a dielectric disk-loaded circularcylindrical waveguide

The radiation pattern of a circular cylindrical waveguide that is loaded inside with periodically spaced dielectric disks is derived by considering the region between two disks as a medium with anisotropic permittivity and using Schelkunoff's equivalence principle. The far-field electric field components and their relationship to cross-polarization ratio are determined. The variation of the latter quantity with the size, spacing, and dielectric constant of the dielectric disks is studied     

网络存储系统容错编码技术进展

专业的大型磁盘存储系统均发展为包含多块磁盘的大型阵列系统。随着系统中的磁盘数目的不断增加,由磁盘失效引起的数据丢失的可能性越来越大。对于由存储系统中部分磁盘失效所引起的数据丢失的问题,目前业界公认的比较好的解决方案是使用冗余容错编码技术来实现磁盘的容错。在工程实践中,目前广泛应用的编码方法大多局限于双容错阵列码。随着系统规模的进一步加大,3容错甚至更多容错的编码方法已引起研究者的重视。今后的5至10年间,对于3容错或多容错的编码方法的研究将会成为新的热点。     

Mode Chart for E-Plane Circulators (Correspondence)

The mode chart of the E-plane junction circulator is given. The geometry considered consists of two ferrite disks placed against the narrow walls at the plane of symmetry of a symmetrical 3-port E-plane waveguide junction. It is experimentally found to exhibit two modes. One of these modes has a resonant frequency which increases with the spacing between the two ferrite disks. The other mode has a resonant frequency which decreases with the spacing between the disks. Both modes are independent of the disk spacing when the spacing is large. It is also found that the frequency of both modes is proportional to the thickness of the ferrite disks. Finally, circulators obtained by magnetizing each of the two modes circulate in opposite directions. Experimental results on a circulator obtained in this way are included.     

Stability of magnetooptical disks under the action of external magnetic fields

The stability of data recorded on magnetooptical disks of different manufacturers is investigated under external magnetic fields oriented along the normal to the disk surface. The recorded data are found to be damaged under magnetic fields with intensities ranging from 300 to 350 kA/m. However, such disks can be reused for information recording. Under the action of magnetic fields with intensities more than 420 kA/m, information on disks is lost and they cannot be reused.     

Magneto-optical properties of self-organized strained InGaAs quantum disks

We have measured the optical properties of self-organized strained InGaAs quantum disks in high magnetic fields. The disks are formed during spontaneous reorganization of a sequence of AlGaAs and strained InGaAs epitaxial films grown on GaAs (311)B substrates by metallorganic vapor-phase epitaxy. The magneto-luminescence properties of these InGaAs quantum disks have been studied for various disks sizes with lateral widths from 100 nm down to 20 nm. We have confirmed that when the lateral confinement exists the exciton binding energy increases even when the spatial extent of the effective potential is greater than the exciton in-plane Bohr radius. This enhancement starts being noticeable when the spatial extent of the potential is two, three times larger than the Bohr radius, where the center-of-mass quantization is negligibly small.     

Ferromagnetic tridisk-coupled resonator and magnetically tunablestripline Y circulator

A ferromagnetic tri-disk-coupled (TDC) resonator is constructed by placing three YIG ferrite disks mutually attached on the circular center conductor. The EM fields in one of the disks is described in terms of expanded circular harmonics with an approximated transformation of derivative, and the EM fields in a TDC resonator is synthesized from the respective constituent fields of the disks, by sum-transformation, regarding three eigenjunctures of the TEC resonator. The synthesized fields include coefficients A, B, and D, which are described as functions of the radis ratio r₀ /r and azimuthal angle φ. The special case in which A=D=0 is treated. Two conditional equations of perfect Y circulation are calculated. Magnetically tunable operation is theoretically analyzed using the conditional curves, and the magnetically tunable operation is examined experimentally with theoretical analysis     

Efficient morphological shape representation with overlapping diskcomponents

This paper proposes a new morphological shape representation algorithm, in which a two-dimensional (2-D) binary shape is represented as a union of certain disks contained in the given shape. The representative disks of different sizes may overlap. But excessive overlapping between them is avoided. The algorithm combines the advantages of the morphological skeleton transform (MST) and the morphological shape decomposition (MSD). The representative disks have simple and well-defined mathematical characterizations. The algorithm is simple and efficient to implement. The experimental results show that the number of representative disks used by our algorithm is significant lower than that used by the MSD. The overlapping level between the representative disks is much lower than that of the MST. A simple procedure can be used to combine the representative disks into more meaningful shape components. These shape components seem to correspond better to the natural shape parts than those generated by the MSD. It is also possible to build a good approximation for a given shape using only a small number of major components.     

IRISTER - magneto-optical disk for magnetically inducedSuperResolution

IRISTER (IRIS Thermal Eclipse Reading) is a remarkable technique for achieving superresolution in optical disks. Two applications of IRISTER are Magnetically induced SuperResolution (MSR) and Premastered optical disk by SuperResolution (PSR). Magnetically induced SuperResolution (MSR) has been realized in magneto-optical disks using exchange-coupled magnetic multilayer films. Two new detection methods have been developed. In the front aperture detection (FAD) method, the heated area in the light spot works as an optical mask so that the signal is read out only from the remaining crescent-shaped area in the spot. In the rear aperture detection (RAD) method, the signal is read out only from the heated area. The cutoff spatial frequency for both types of detection is more than two times higher than that in conventional detection. A high C/N of 42 dB is obtained in the MSR disks by both methods for a mark length of 0.3 μm, which is much shorter than the optical limit. Premastered optical disk by SuperResolution (PSR) has been realized in read-only optical disks using phase-change materials. In the front aperture detection (FAD) method for PSR, the prerecorded signal is read out only from the high reflective crescent-shaped area in the light spot, because the reflectance of the heated area is too low. A C/N of 51 dB for a mark length of 0.3 μm has been obtained for the PSR disk     

超分辨近场结构光盘的研究进展

超分辨近场结构(Super-RENS)光数据存储方案在近场超高密度光数据存储方面具有巨大的发展潜力和广阔的发展前景。在此方案中,超分辨结构的非线性层起着至关重要的作用。本文简述了Super-RENS光盘中两种类型光盘的结构及优点,并着重介绍了其工作机理的研究进展。     

Morphological decomposition of 2-d binary shapes into modestly overlapped octagonal and disk components.

One problem with several leading morphological shape representation algorithms is the heavy overlapping among the representative disks of the same size. A shape component formed by grouping connected disk centers may use many heavily overlapping disks to represent a simple shape part. Sometimes, these representative disks form complicated structures. A generalized skeleton transform was recently introduced which allows a shape to be represented as a collection of modestly overlapped octagonal shape parts. However, the generalized skeleton transform needs to be applied many times. Furthermore, an octagonal component is not easily matched up with another octagonal component. In this paper, we describe a octagon-fitting algorithm which identifies a special maximal octagon for each image point in a given shape. This transform leads to the development of two new shape decomposition algorithms. These algorithms are more efficient to implement; the octagon-fitting algorithm only needs to be applied once. The components generated are better characterized mathematically. The disk components used in the second decomposition algorithm are more primitive than octagons and easily matched up with other disk components from another shape. The experiments show that the new decomposition algorithms produce as efficient representations as the old algorithm for both exact and approximate cases. A simple shape-matching algorithm using disk components is also demonstrated.     

Choosing an optimal set of libraries [software reliability]

This paper presents optimization models for selecting a subset of software libraries, viz, collections of programs, residing on floppy disks or compact disks, available on the market. Each library contains a variety of programs whose reliabilities are assumed to be known. The objective is to maximize the reliability of the computer system subject to a budget constraint on the total cost of the libraries selected. The paper includes six models, each of which applies to a different software structure and assumptions. A detailed branch and bound algorithm for solving one of the six models is described; it contains a simple greedy-procedure for generating an initial solution     

Efficiencies of superconducting small antennas connected tolossless disks over lossy groundplanes

Superconducting electrically small monopoles and half loops over lossy groundplanes with perfectly conducting disks attached to their bases are modeled using a moment method incorporating Sommerfeld-type integrals. It is shown that improved efficiency is obtainable by incorporating these disks, compared with cases where the antennas are connected directly to the groundplanes     

Spatial ordering of self-organized InGaAs/AlGaAs quantum disks on GaAs (311)B substrates

We report the control of self-organization of In_xGa_1−xAs/AlGaAs quantum disks on GaAs (311)B surfaces using a novel technique based upon lithography-defined SiN dot arrays. A strained InGaAs island array selectively grown using the SiN dots provides periodic strain field. When the pitch of lateral ordering corresponds with the period of the strain field, self-organized quantum disks stacked on the InGaAs islands are precisely arranged just as the buried SiN dot array. The spacing of the array element is 250–300 nm (x = 0.3) and around 150 nm (x = 0.4). Vertical alignment by strain is achieved at a very thick (95 nm) separating layer. Characterization using atomic force microscopy reveals the size-fluctuation of disk is dramatically improved with spatial ordering.     

Magnetooptics: A thermomagnetic recording technology

Erasable magnetooptic (MO) recording is viewed as a possible successor to electromagnetic recording that is used today in high-performance disk drives for mainframe computers, hard disks, and floppy disks for personal computers and magnetic tape drives. A large number of rare earth-transition metal alloys have been investigated for use as the magnetic recording material. The properties of the films are very sensitive to the film deposition processing parameters. Accelerated life tests show that there are magnetooptic materials that do have all of the necessary properties and stability for use in computer digital storage.     

Reflection and transmission operators for strips or disks embeddedin homogenous and layered media

A notation is proposed to simplify the solution of scattering by strips and disks. Vector Fourier transforms are used and a double dot product for inner products in an uncountably infinite dimensional linear vector space is introduced. Scattering by a strip or a disk is characterized using a reflection operator and a transmission operator that relate the continuum of scattered waves to a continuum of incident waves. After the reflection operator for a single strip or disk is derived, it is shown how the reflection operator for a strip or disk in the presence of another reflecting medium, e.g. a layered medium, can be derived. The scattering by N strips or disks in a homogeneous medium is also discussed. The reflection operator for an embedded strip or disk in a layered medium is then derived. The method can be generalized to N strips or disks embedded in a layered medium and to a slot or aperture     

N31型磷酸盐钕玻璃在神光-Ⅱ实验装置中的应用

神光 Ⅱ实验装置经过一段时间的改进 ,特别是在光束质量方面的提高 ,填充因子已经达到 5 0 %左右 ,光束的空间分布比较均匀 ,又使用新的N3 1型磷酸盐钕玻璃 ,荧光寿命从 2 5 0 μs提高到 330 μs,使其增益能力大大地提高 ,6片N3 1型磷酸盐钕玻璃片与厚度相同的 8片N2 1老型磷酸盐钕玻璃片相比 ,增益增加约 10 %左右     

磁盘阵列上虚拟磁盘的管理

随着计算机技术的发展,数据量急速增如,数据管理成为一个研究热点。磁盘阵列的出现极大地改善了数据管理的性能。在使用磁盘阵列时,往往把它划分为多个逻辑磁盘,磁盘的大小不能改变。这种方法降低了磁盘空间的利用效率。为了解决这个问题,可以把磁盘阵列划分为一个或多个共享存储池。每个共享存储池管理多个虚拟磁盘。这些虚拟磁盘共同使用共享存储池的磁盘空间。为了协调多个虚拟磁盘同时向共享存储池读写数据的问题,设计了一个调度算法。使用这种方法,实现了对磁盘阵列的有效管理。