• 제목/요약/키워드: random variation

검색결과 623건 처리시간 0.027초

Stochastic thermo-mechanically induced post buckling response of elastically supported nanotube-reinforced composite beam

  • Chaudhari, Virendra Kumar;Shegokar, Niranjan L.;Lal, Achchhe
    • Advances in aircraft and spacecraft science
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    • 제4권5호
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    • pp.585-611
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    • 2017
  • This article covenants with the post buckling witticism of carbon nanotube reinforced composite (CNTRC) beam supported with an elastic foundation in thermal atmospheres with arbitrary assumed random system properties. The arbitrary assumed random system properties are be modeled as uncorrelated Gaussian random input variables. Unvaryingly distributed (UD) and functionally graded (FG) distributions of the carbon nanotube are deliberated. The material belongings of CNTRC beam are presumed to be graded in the beam depth way and appraised through a micromechanical exemplary. The basic equations of a CNTRC beam are imitative constructed on a higher order shear deformation beam (HSDT) theory with von-Karman type nonlinearity. The beam is supported by two parameters Pasternak elastic foundation with Winkler cubic nonlinearity. The thermal dominance is involved in the material properties of CNTRC beam is foreseen to be temperature dependent (TD). The first and second order perturbation method (SOPT) and Monte Carlo sampling (MCS) by way of CO nonlinear finite element method (FEM) through direct iterative way are offered to observe the mean, coefficient of variation (COV) and probability distribution function (PDF) of critical post buckling load. Archetypal outcomes are presented for the volume fraction of CNTRC, slenderness ratios, boundary conditions, underpinning parameters, amplitude ratios, temperature reliant and sovereign random material properties with arbitrary system properties. The present defined tactic is corroborated with the results available in the literature and by employing MCS.

소나무 군집안의 주요 구성종의 미분포와 종간 상관 (Pattern and association within Pinus densiflora communities in Kyunggi Province, Korea)

  • 오계칠
    • Journal of Plant Biology
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    • 제13권1호
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    • pp.33-46
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    • 1970
  • Pinus densiflora stands are common secondary forest communities on infertile soils in Korea. The stands are results of long severe past biotic pressure such as cutting, burning and grazing. These could be regarded as biotic climax in Korea. Because of their prevalent occurrence, relatively simple species and age composition, and their domestic economic importance, study of their distributional patterns may give some basic knowledge for better utilization of land resources in Korea. To detect distributional patterns and interspecific associations ten pine stands, each of which was homogenious with respect to topography and physiognomy, were subjectively selected from pine stands in Kyunggi Province near Seoul in 1969 and were made object of this study. Four contiguous systematic samples of count for trees, shrubs and seedlings from belt transects were collected from homogeneous areas within ten natural pine stands. The belt transect was 64m or 128m in length, and 1m, 2m or 4m in width. Basic units within the transect ranged from 64 to 256. The data from the contiguous transects were analysed in terms of multiple split-plot experiment. Departure from randomness of stem distribution, i.e., pattern, was tested in terms of variance mean ratio. For the detection of association between species, correlation coefficient was calculated for different block sizes. The values of ${\gamma}$ were tested by the usual t-test. Fine trees within one of the stands showed significant regular distribution through out the blocks. Within other eight stands pines were randomly distributed at basic unit with 4$\times$4m, 2$\times$2m, 2$\times$1m and 1$\times$1m. One significantly clumped distribution at basic unit 2$\times$2m, however, was observed from one of the pine stands. These randomly distributed groups were themselves significantly regularly distributed throughout the blocks for four pine stands. For the other four pine stands, in addition to the random distribution at the basie unit(the primary random group), randomly distributed groups with 32m dimension(the secondary random groups) were also observed. Both the primary and the secondary random groups were significantly regularly distributed at the rest of blocks. Pine seedlings were not distributed randomly thoughout the blocks. Within three of the ten stands they were contagiously distributed. Important shrub species underneath pines such as Querus serrata, Q. acutissima, Leapedeza intermedia, Rhododendron Yedoense var. poukhanenae, Juniperus utilis, Rhododendron mucronulatum var. ciliatum shnwed consistently similar distributional pattern with the pine at each stand. The shrub species pairs; Rhododendron Yedoense var. poukhanenae/Quercus serrata, Rhododendron mucronulatum var. ciliatum/Lespedeza intermedia were significantly negatively associated from 1m to 4m dimensional block sizes but became significantly positively associated from 8m sized blocks on. On the other hand the shrub species pairs; Lespedeza intermedia/Robinia Pseudoacacia, and Lespedeza bicolor var, japonica/Lespedeza intermedia were also significnalty negatively associated from 1m to 8m sized blocks but became significantly positively associated from 16m sized blocks on. The associational pattern between Rhododendron mucronul tun var. poukhanenae and Lespedeza intermedia was not consistent throughout the stands. In some stands negative associations were observed throughout the blocks except NS 32. From these observatons micro-edaphic variation within the pine stands seems not to be great enough to cause distributinal difference of pine trees within the ten pine stands. Among each species and pine seedings, however, the edaphic variation within the pine stands may be great enought to cause distributional variation.

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Analysis of Genetic Variation in Botrytis cinerea Isolates Using Random Amplified Polymorphic DNA Markers

  • Choi, In-Sil;Kim, Dae-Hyuk;Lee, Chang-Won;Kim, Jae-Won;Chung, Young-Ryun
    • Journal of Microbiology and Biotechnology
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    • 제8권5호
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    • pp.490-496
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    • 1998
  • Random amplified polymorphic DNA (RAPD) markers were used to survey genetic variability among 34 Botrytis cinerea isolates from nine different host plants in Korea. For RAPD analysis, 115 arbitrary decamer primers were initially screened for polymorphic major DNA bands with 11 representative B. cinerea isolates. Eleven primers that initially detected polymorphisms were tested a second time with additional 23 isolates of B. cinerea as well as one isolate of Botrytis squamosa as an outgroup. The RAPD analyses revealed that all isolates except one showed different molecular phenotypes. Dendrograms obtained from dissimilarity matrices using the unweighted paired group method of arithmetic means (UPGMA) showed the 36.4% to 90.0% similarity among all B. cinerea isolates. The B. squamosa isolate showed the least similarity to all B. cinerea isolates. The cluster analyses indicated no correlation among all the characteristics examined including molecular phenotypes, host and geographic origins, year of isolation, or pathogenicity. The RAPD data suggest that a high level of genetic variation exists among Korean populations of B. cinerea and it seems to be caused by heterokaryosis among preexisting molecular phenotypes.

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Tilt variation and wake turbulence in the otter board of a bottom trawl during fishing operations

  • KIM, Yong-Hae
    • 수산해양기술연구
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    • 제53권4호
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    • pp.337-348
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    • 2017
  • The tension of warp from trawler and sea-floor contact can generate tilt and wake turbulence around otter boards. Preliminary measurements of otter board tilt and 3-D flow velocity during bottom trawl operations were taken using a vector instrument to investigate the effects of wake turbulence at the trailing edge of the otter board. Tilt data (i.e., yaw, pitch, and roll) at 1 Hz and flow data (velocities in the towing, lateral, and vertical directions) at 16 Hz were analyzed to determine their periods and amplitudes using global wavelet and peak event analyses. The mean period (${\pm}standard$ deviation) of the tilt from the peak event analysis ($5{\pm}2s$) was longer or double than that of flow velocity ($3{\pm}2s$). The two periods also had a significant linear relationship. The turbulence rate of flow was 30-50% at the trailing edge and was closely related to roll deviation. The frequency of phase difference ratios (i.e., peak time differences between tilts and flow periods) was significantly different from random occurrence in two trials, possibly due to side tidal effects. However, in the other trials, flow peaks were random, as shown by the even peak times between tilts and flows. Future studies should focus on reducing tilt variation, wake turbulence, and bottom contact to stabilize otter board motion.

Intraspecific variations of the Yam (Dioscorea alata L.) based on external morphology and DNA marker analysis

  • Chang, Kwang-Jin;Yoo, Ki-Oug;Park, Cheol-Ho;Lim, Hak-Tae;Michio Onjo;Park, Byoung-Jae
    • Plant Resources
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    • 제3권3호
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    • pp.211-218
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    • 2000
  • Intraspecific genetic relationship of 19 variation types of the Yam (Dioscorea alata) classified by their external morphological characteristics such as leaf and tuber shape were assessed by DNA using random and specific primer. Twenty two out of 113 primers (100 random[10-mer] primers, two 15 mer [M13 core sequence, and (GGAT)$_4$ sequence]) had been used in PCR-amplification. Only 12 primers, however, were success in DNA amplification in all of the analyzed plants, resulting in 93 randomly and specifically amplified DNA fragments. The analyzed taxa showed very high polymorphisms(69 bands, 71.0 %), allowing individual taxon to be identified based on DNA fingerprinting. Monomorphic bands among total amplified DNA bands of each primer was low under the 50%. Similarity indices between accessions were computed from PCR(polymerase chain reaction) data, and genetic relationships among intraspecific variations were closely related at the levels ranging from 0.66 to 0.90. These DNA data were not matched well with those of morphological characters since they were divided into two major groups at the similarity coefficient value of 0.70. Therefore, Grouping of species into variation types by mainly morphological charactistics was suggested unreasonable.

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Statistical evaluation of drift demands of rc frames using code-compatible real ground motion record sets

  • Kayhan, Ali Haydar;Demira, Ahmet
    • Structural Engineering and Mechanics
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    • 제60권6호
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    • pp.953-977
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    • 2016
  • Modern performance-based design methods require ways to determine the factual behavior of structures subjected to earthquakes. Drift ratio demands are important measures of structural and/or nonstructural damage of the structures in performance-based design. In this study, global drift ratio and interstory drift ratio demands, obtained by nonlinear time history analysis of three generic RC frames using code-compatible ground motion record sets, are statistically evaluated. Several ground motion record sets compatible with elastic design spectra defined for the local soil classes in Turkish Earthquake Code are used for the analyses. Variation of the drift ratio demands obtained from ground motion records in the sets and difference between the mean of drift ratio demands calculated for ground motion sets are evaluated. The results of the study indicate that i) variation of maximum drift ratio demands in the sets were high; ii) different drift ratio demands are calculated using different ground motion record sets although they are compatible with the same design spectra; iii) the effect of variability due to random causes on the total variability of drift ratio demands is much larger than the effect of variability due to differences between the mean of ground motion record sets; iv) global and interstory drift ratio demands obtained for different ground motion record sets can be accepted as simply random samples of the same population at %95 confidence level. The results are valid for all the generic frames and local soil classes considered in this study.

RAPD를 이용한 겨자의 유전적 다양성과 집단구조 (Genetic Diversity and Population Structure of Brassica juncea by Random Amplified Polymorphic DNA (RAPD))

  • 오영희;문성기;채양희;홍화진;조철민;박소혜;허만규
    • 생명과학회지
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    • 제20권10호
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    • pp.1538-1543
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    • 2010
  • 본 연구는 우리나라 겨자 17집단에 대한 유전적 다양도와 집단구조를 조사하였다. 60개의 다형성 좌위와 18개 단형성 좌위가 발견되었다. 다형성 밴드의 비율은 전남 진도 집단이 가장 높았으며 재배종이 가장 낮았다. 대립유전자좌위의 수는 1.221이였으며 유효한 대립유전자좌위의 수는 1.167이였다. 이 종의 전형적인 집단은 작고 격리되어 낮은 유전적 다양도를 가지고 있었다. 전체 다양도는 0.347이였으며 집단 내 다양도는 0.141이였다. 집단간분화를 나타내는 척도는 0.589였다. 아는 58.9%의 다양도가 집단간에 있음을 시사한다. 세대 간 이주하는 개체수는 0.617로 낮았다. RAPD는 겨자 집단을 구분하는데 유익하였다.

Reverse Random Amplified Microsatellite Polymorphism Reveals Enhanced Polymorphisms in the 3' End of Simple Sequence Repeats in the Pepper Genome

  • Min, Woong-Ki;Han, Jung-Heon;Kang, Won-Hee;Lee, Heung-Ryul;Kim, Byung-Dong
    • Molecules and Cells
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    • 제26권3호
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    • pp.250-257
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    • 2008
  • Microsatellites or simple sequence repeats (SSR) are widely distributed in eukaryotic genomes and are informative genetic markers. Despite many advantages of SSR markers such as a high degree of allelic polymorphisms, co-dominant inheritance, multi-allelism, and genome-wide coverage in various plant species, they also have shortcomings such as low polymorphic rates between genetically close lines, especially in Capsicum annuum. We developed an alternative technique to SSR by normalizing and alternating anchored primers in random amplified microsatellite polymorphisms (RAMP). This technique, designated reverse random amplified microsatellite polymorphism (rRAMP), allows the detection of nucleotide variation in the 3' region flanking an SSR using normalized anchored and random primer combinations. The reproducibility and frequency of polymorphic loci in rRAMP was vigorously enhanced by translocation of the 5' anchor of repeat sequences to the 3' end position and selective use of moderate arbitrary primers. In our study, the PCR banding pattern of rRAMP was highly dependent on the frequency of repeat motifs and primer combinations with random primers. Linkage analysis showed that rRAMP markers were well scattered on an intra-specific pepper map. Based on these results, we suggest that this technique is useful for studying genetic diversity, molecular fingerprinting, and rapidly constructing molecular maps for diverse plant species.