• Title/Summary/Keyword: Gravitation

Search Result 84, Processing Time 0.03 seconds

Invasion of Ambrosia artemisiifolia L. (Compositae) in the Ukrainian Carpathians Mts. and the Transcarpathian Plain (Central Europe)

  • Song, Jong-Suk;Prots, Bohdan
    • Animal cells and systems
    • /
    • v.2 no.2
    • /
    • pp.209-216
    • /
    • 1998
  • The invasion of Ambrosia artemisiifolia in the Ukrainian Carpathians Mts. and the Transcarpathian Plain in Central Europe was reconstructed on the basis of floristic records. The first spontaneous occurrence was dated from the beginning of the 1940s. Within the next 55 year period, the distributional spread speed of the species was of 67.6 $km^2/y$ (by the average data). The occupied area by A. artemisiifolia in the range of the studied areas is about $3716.5km^2$ now. The features of behavior of the invader and the habitat preference were determined. The frequency of occurrence by sociologic-ecological classification was carried out. The generalized model of correlations among the gravitation, the active temperature sum and the disturbance gradients and the frequency of occurrence of the species was presented. The scheme of the invasion stages of A. artemisiifolia is reflected in the population status changes of the species during the areal dynamics.

  • PDF

Separation and Characterization of Dust and Ground Water Particulates Using Gravitational SPLITT Fractionation.

  • Lee, Seung Ho;Park, Hui Yeong;Lee, Sang Geun;Yong, Seong Gwon;Eum, Cheol Hun
    • Bulletin of the Korean Chemical Society
    • /
    • v.22 no.6
    • /
    • pp.616-622
    • /
    • 2001
  • Split-flow thin (SPLITT) cell Fractionation(SF) is a technique that allows separation of particulates and macromolecules into two fractions. A gravitational SF(GSF) system is constructed and tested for its applicability for separation of dust and ground water particulates. When tested with polystyrene latex particles, experimental data were in good agreements with theory. The 9.8 and 21.4㎛ polystyrene particles were successuflly separated in a continuous mode, where the mixture is continuously fed into the GSF channel allowing separation in a large sacle. The GSF system is successfully applied to continuous separation of dust and ground water particels based on the sedimentation coefficient, which is closely related to the particle size. The separations were confirmed by microscopy and energy-dispersive X-ray (EDX) analysos.

Stress field around axisymmetric partially supported cavities in elastic continuum-analytical solutions

  • Lukic, D.;Prokic, A.;Anagnosti, P.
    • Structural Engineering and Mechanics
    • /
    • v.35 no.4
    • /
    • pp.409-430
    • /
    • 2010
  • The present paper will be concerned to the investigation of the stress-strain field around the cavity that is loaded or partially loaded at the inner surface by the rotationally symmetric loading. The cavity of the spherical, cylindrical or elliptical shape is situated in a stressed elastic continuum, subjected to the gravitation field. As the contribution to the similar investigations, the paper introduces the new function of loading in the form of the infinite sine series. Besides, in this paper the solution of stresses around an oblong ellipsoid cavity, has been obtained using appropriate curvilinear elliptical coordinates. This analytical approach avoids the solutions of the same problem that lead to expressions that contain rather complex integrations. Thus the presented solutions provide the applicable and explicit expressions for stresses and strains developed in infinite series with easily determinable coefficients by the use of contemporary mathematical packages. The numerical examples are also included to confirm the convergence of the obtained solutions.

Selection Criteria of Harvesting and Logging Methods in Consideration of Forest Terrain Characteristics (산림지형특성(山林地形特性)을 고려한 산림수확방법(山林收穫方法) 및 집재방법(集材方法)의 선정기준)

  • Kim, Ki Weon
    • Journal of Korean Society of Forest Science
    • /
    • v.82 no.2
    • /
    • pp.195-206
    • /
    • 1993
  • The purpose of this study is to provide a basis for establishing regional harvesting systems that ist the prerequisites for the forest mechanization. The factors restricting to the forest harvesting and logging methods from topographical aspects are studied for this purpose. Three main harvesting methods studied in this paper are : shortwood method, longwood method and full tree method. This study shows : the shortwood method is suitable for low, the longwood method for medium, the full tree method for high topographical conditions. For the logging methods, the focus of the study is on various ground based logging systems by animalpower, manpower, gravitation, wheeled & crawler vehicle and cable. The factors limiting the coverage of logging operation are slope and logging distance. The cable crane logging methods are classified by logging distance into short distance(to 300 or 400m), middle distance(to 700 or 800m) and long distance cable crane methods (over 700 or 800m). The wheeled vehicle method shows serious damages to forest resources, whereas the logging by log-line of the gravitation logging method and cable crane method tend to minimize such damages. The wheeled & crawler vehicle method also shows difficult to apply in the high slope conditions, whereas cable crane method can be applied to maximum 120% steep slope and uphill conditions.

  • PDF

DARK ENERGY REFLECTIONS IN THE REDSHIFT-SPACE QUADRUPOLE

  • NISHIOKA HIROAKI;YAMAMOTO KAZUHIRO;BASSETT BRUCE A.
    • Journal of The Korean Astronomical Society
    • /
    • v.38 no.2
    • /
    • pp.175-178
    • /
    • 2005
  • We show that next-generation galaxy surveys such as KAOS (the Kilo-Aperture Optical Spectro-graph)will constrain dark energy even if the baryon oscillations are missing from the monopole power spectrum and the bias is scale- and time-dependent KAOS will accurately measure the quadrupole power spectrum which gives the leading anisotropies in the power spectrum in redshift space due to peculiar velocities, the finger of God effect, as well as the Alcock-Paczynski effect. The combination of monopole and quadrupole power spectra powerfully breaks the degeneracy between the bias parameters and dark energy and, in the complete absence of baryon oscillations ($\Omega$b = 0), leads to a roughly $500\%$ improvement in constraints on dark energy compared with the monopole spectrum alone. As a result, for KAOS the worst case with no oscillations has dark energy errors only mildly degraded relative to the ideal case, providing insurance on the robustness of KAOS constraints on dark energy. We show that nonlinear effects are crucial in correctly evaluating the quadrupole and significantly improving the constraints on dark energy when we allow for multi-parameter scale-dependent bias.

A Study on The Process of Design Idea - Focused on An Expansion and A Diversity of Idea (디자인 아이디어 전개에 관한 연구 - 사고의 확장성과 다의성을 중심으로)

  • 이한성
    • Archives of design research
    • /
    • v.17 no.2
    • /
    • pp.67-76
    • /
    • 2004
  • The main stream of consumption about the products is tend to transfer from low price value with mass production, to the second value of products, such as pleasure, familiarity, humor, and metaphor. This second value is closely connected to a redundancy which are also related to modern science as well as product design. These terms such as matrials, identity, and gravitation, disappeared gradually, and these are substituted with an uncertainty principle, a fortuity, a contradictory concept, entropy etc. In sum this study focuses on the tendency of intelligency issue the recent design trends. This result shows that The 4th Column Thinking and Formation System which is related to an expansion and diversity of design intellectual ideas.

  • PDF

Spray Deposit Distribution of a Small Orchard Sprayer (소형 과수방제기 살포입자의 부착량 분포)

  • Koo, Young-Mo
    • Journal of Biosystems Engineering
    • /
    • v.32 no.3
    • /
    • pp.145-152
    • /
    • 2007
  • Uniformity of spray deposit is one of the important factors in spray performance affecting efficacy of pest management. Distributions of spray deposit on artificial targets were measured and analyzed to enhance the efficiency of spray application. The research was studied to understand the deposition characteristics of spray droplets and to determine the optimum conditions of chemical application. The deposit and its pattern by the lower fan speed was more uniform and higher than that by the higher fan speed. The upward blasting distance was limited within 3 m, but the limit to the ground level was expanded the distance more than 3.5 m because of the accumulated droplets. When the fan speed was higher at the distance of 2.5 m, deposit reached to maximum. When the distance increased, deposit was getting lower. At the both fan speeds, the deposit was concentrated below $30^{\circ}$ because of the gravitation and the resistance of wind. This research can be useful in designing an orchard sprayer and its operation for various tree canopies. To achieve a uniform distribution of deposit using the air-blast type orchard sprayer, the application rate from the middle boom should be increased as the air velocity to the upward increased. The spray rate to the side boom should be limited in a minimal level.

The Effect of Meteorological Factors on Variation and Temporal and Spatial Characteristics of $NO_2$ Concentration in Pusan Area (부산광역시에서의 $NO_2$농도 특성 및 기상 영향인자 분석)

  • 이화운;김유근;장난심;이용희
    • Journal of Environmental Science International
    • /
    • v.8 no.4
    • /
    • pp.465-471
    • /
    • 1999
  • The concentration of air pollution in a large city such as Pusan has been increased every years due to the increase on fuel consumption at factories and by vehicles as well as the gravitation of the population. In this study, we have analyzed $NO_2$ concentration data and various data of meteorological factors during 1994-1997 to investigate the characteristics of $NO_2$ concentration and how the high $NO_2$ concentration is generated under the meterological condition. According to the study, $NO_2$ peak concentration at most sites occured about 1h later after the rush hour. In the characteristics of emissions in sites, sinpyeong-dong was highly contributed to point source while the other sites were highly contributed to line source. The high $NO_2$ concentration had high generation probability when temperature contained typical seasonal characteristics and wind speed was low. Using the relationship between meteorological factors and the daily average $NO_2$ concentration, correlation analysis was practiced. the seasonal variation of the daily average $NO_2$ concentration was correlated with air temperature, solar radiation and wind speed, but the correlation coefficient between meteorological factors and the daily average $NO_2$ concentration was not so much high. Thus we have known that the daily average $NO_2$ concentration is partially explained by meteorological factors.

  • PDF

Dynamic simulation of a Purse seine net behavior for hydrodynamic analysis (유체역학적 해석을 위한 선망 어구 운동의 동적 시뮬레이션)

  • 김현영;이춘우;차봉진;김형석;권병국
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.38 no.2
    • /
    • pp.172-178
    • /
    • 2002
  • This study presents a dynamic simulation of a purse seine net behavior Mathematical model suitable for purse seining, which is based on data from a series of previous simulations, various field experiments, is modelized as a set of mass-spring system. In this model, a number of meshes are approximated as one mass point, each of which connected to its neighbors by massless springs, the equations of motion are derived from considering internal force from the springs and external forces such as resistance and gravitation. This simulation shows the quantitative state on every mass point of the net and purse line during the shooting and pursing phases. So it is possible that performance of a purse seine net be analyzed using various and evolving parameters such as the shooting speed, the hauling speed, the size or type of the sinker, float and twine, also the hanging ratio etc.

A Study on the Deterioration Factors of Masonry Buildings in Seoul (서울 지역 조적조 건축물의 열화요인에 관한 연구)

  • Kwon, Ki-Hyuk;Mok, Jin-Woo;Kim, Kwang-Koo
    • Journal of the Korean Society of Hazard Mitigation
    • /
    • v.3 no.3 s.10
    • /
    • pp.173-181
    • /
    • 2003
  • Because of the gravitation of population toward large cities, a number of masonry buildings have been constructed since 1960's. They have been rapidly deteriorated as time passed by. Therefore the purpose of this paper is to present basic data on timeworn masonry buildings which were managed by the Jung, Mapo and Dobong district in Seoul Metropolitan and to analyse their deterioration factors as well as interrelation. Through this study, masonry buildings have many problems with foundation and crack is the most effective to deterioration. Also, the store buildings are the weakest structure type and the structure grade have an interrelation with occupancy type mere than any other factors.