The magneto-transport properties of an individual single crystalline Bi nanowire grown by aspontaneous growth method are reported. A four-terminal device based on an individual 400-nm-diameternanowire was successfully fabricated using a plasma etching technique that removed an oxide layer that hadformed on the surface of the nanowire. Large transverse ordinary magnetoresistance (1401%) and negativelongitudinal ordinary magnetoresistance (−38%) were measured at 2K. It was observed that the period ofShubnikov-de Haas oscillations in transverse geometry was 0.074T−1, 0.16T−1 and 0.77T−1, which is in goodagreement with those of bulk Bi. However, it was found that the period of SdH oscillation in longitudinalgeometry is 0.24T−1, which is larger than the value of 0.16T−1 reported for bulk Bi. The deviation is attributableto the spatial confinement arising from scattering at the nanowire surface boundary.

The basic objective of helioseismology is to determine the structure and the dynamics of the Sun by analysing the frequency spectrum of the solar oscillations. Accurate frequency measurements provide information that enables us to probe the solar interior structure and the dynamics. Therefore the frequency of the solar oscillation is the most fundamental and important information to be extracted from the solar oscillation observation. This is why many efforts have been put into the development of accurate data analysis techniques, as well as observational efforts. To test one's data analysis method, a realistic artificial data set is essential because the newly suggested method is calibrated with a set of artificial data with predetermined parameters. Therefore, unless test data sets reflect the real solar oscillation data correctly, such a calibration is likely incomplete and a unwanted systematic bias may result in. Unfortunately, however, commonly used artificial data generation algorithms insufficiently accommodate physical properties of the stochastic excitation mechanism. One of reason for this is that it is computaionally very expensive to solve the governing equation directly. In this paper we discuss the nature of solar oscillation excitation and suggest an efficient algorithm to generate the artificial solar oscillation data. We also briefly discuss how the results of this work can be applied in the future studies.

We present preliminary numerical simulations of tilted-disk accretion around a rotating black hole. Our goal is to explore whether hydrodynamic instabilities near the Bardeen-Petterson radius could be responsible for generating moderate-frequency quasi-periodic oscillations in X-ray binaries. We review the relevant general relativistic hydrodynamic equations, and discuss preliminary results on the structure and dynamics of a thin, Keplerian disk.

Assuming that the solar activity and the solar cycle phenomena may be manifestations of global torsional MHD oscillations, we compute the Alfven wave travel times along the field lines in the five models of magnetic field described in the following text. For all these models, we compute standard deviation and it's ratio to mean Alfvenic wave travel times. The last two models yield the smallest relative bandwidth for the frequencies of the MHD oscillations. However, the last model is the only admissible one which can sustain global Alfvenic oscillations with well defined frequency for the fundamental mode

Two-component models (normal star and degenerate star components) are the simplest realization of clusters with a mass spectrum because the high mass stars quickly evolve off leaving degenerate stars behind, while low mass stars survive for a long time as main-sequence stars. In the present study we examine the post-collapse evolution of globular clusters using two-component Fokker-Planck models that include three-body binary heating. We confirm that a simple parameter є ≡ (Etot/trh)/(Ec/trc) well describes the occurrence of gravothermal oscillations of two-component clusters. Also, we find that the degree of instability depends on the steepness of the mass function such that clusters with a steeper mass function are less exposed to instability.

In the present study a two-mode, separately concurring resonant cavity model is proposed for theoretical interpretation of the 3 minute umbral oscillation. The proposed model has been investigated by calculating the transmission coefficients of the waves propagating through the umbral photosphere (photospheric weak-field cavity) and chromosphere (chromospheric strong-field cavity) into the corona, for 3 different umbral model atmospheres by Staude (1982), Beebe et al. (1982) and Avrett (1981). In computing the transmission coefficients we made use of multi-layer approximation by representing the umbra] atmosphere by a number of separate layers with (1) temperature varying linearly with depth and (2) temperature constant within each layer. The medium is assumed to be compressible, non-viscous, perfectly conducting under gravity. The computed resonant periods, transmission spectra, phase spectra, and kinetic energy density of the waves associated with the oscillations are presented in comparison with the observations and their model dependent characteristics are discussed.

오늘날에 항만부진동의 문제는 대형선박이 입출항하는 항만의 설계에서 가장 현저한 인자로 작용한다. 연안 항만에서 탄성체의 삭으로 계류하고 있는 대형 선박은 장주기파랑과 계류시스템간의 공진으로 인해 종종 이탈되기도 한다. 특히, 장주기 파랑의 증폭비가 현저해지면 화물의 하역에 장애를 가져오며 계류삭이 절단되는 경우도 발생한다 이중 국내에서 부진동의 문제가 가장 현저하게 나타난 항만은 포항신항이며, 이에 따른 문제가 도선사 협회나 지역해양수산청으로부터 보고되고 있다. 그러나 이 항만에서 부진동을 야기하는 장주기 파랑의 내습을 막는 것은 어렵다. 더구나 정부는 이미 포항신항에서 발생하고 있는 이러한 문제점을 해결하지 않고 영일만의 입구에서 신항만 건설을 이미착수해놓고 있다. 본 연구는 영일만 입구의 4.1km에 달하는 방파제 건설과 신항만 계획을 반영하여 이들이 항만 부진동에 어떠한 변화를 가져오는 것인가에 대해 다룬다. 사용한 수치기법은 확장완경사방정식을 사용한 표준형식을 갖춘 것으로 수치실험결과를 이전 연구를 통해 이루어진 관측치와 비교하였으며, 이것이 어느 수준까지의 토론으로 이끌어 낼 것이며 장래 항만개발에 변화를 가져올 것으로 본다.

In order to simulate and investigate the major characteristics of El Nino/Southern Oscillation(ENSO) and Madden Jullian Oscillation(MJO), an intermediate type atmosphere-ocean coupled model is developed and their results are examined. The atmosphere model is a time-dependent non-linear perturbation moist model which can determine the internal heating for itself. The counterpart of the atmosphere model is GCM-type tropical ocean model which has fine horizontal and vertical grid resolutions. In the coupled experiment, warm SST anomaly and increased precipitation and eastward wind and current anomalies associated with ENSO and MJO are properly simulated in Pacific and Indian Oceans. In spite of some discrepancies in simulation MJO, the observed atmospheric and oceanic low-frequency characteristics in the tropics are successfully identified. Among them, positive SST anomalies centered at the 100m-depth of tropical eastern-central Pacific due to the eastward advection of warm water and reduced equatorial upwelling, and negative anomalies in the Indian and western Pacific seem to be the fundamental features of tropical low-frequency oscillations.