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  • STRUCTURAL MECHANICS  (7)
  • Madagascar  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Molecular evolutionary relationships of three genera of nesomyinae, endemic rodent taxa from madagascar (1996)
    Springer
    Journal of mammalian evolution 3 (1996), S. 239-260 
    Details
    ISSN: 1573-7055
    Keywords: Nesomyinae ; Muroidea ; 12S rDNA ; Madagascar ; DNA hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationships of Nesomyinae, a group of murid rodents endemic to the island of Madagascar, were investigated with two comparative molecular approaches. Compared to those of other muroid rodents representing Murinae, Cricetinae, Cricetomyinae. Arvicolinae, and Sigmodontinae, complete sequences of the 12S rRNA mitochondrial gene suggest that the Malagasy nesomyinesMacrotarsomys andNesomys are monophyletic and that their sister-group among the taxa analyzed isCricetomys. A limited series of DNA/DNA hybridization experiments extends these observations to a third nesomyine genus,Eliurus, and a second cricetomyine taxon,Saccostomus. By relating the amounts of overall genomic divergence with geological time as calibrated by theMus/Rattus dichotomy estimated at 12–14 My, the oldest within-Nesomyinae dichotomy is estimated to be 10.8 to 12.6 My. Thus, these three genera of Malagasy nesomyine rodents appear to be a rather ancient offshoot from African ancestors whose Recent relatives are Cricetomyinae. This preliminary observation should be confirmed by sampling additional genera of nesomyines and additional representatives for other subfamilies of African muroids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01458182
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Phylogenetic relationships of the endemic malagasy carnivoreCryptoprocta ferox (Aeluroidea): DNA/DNA hybridization experiments (1993)
    Springer
    Journal of mammalian evolution 1 (1993), S. 169-185 
    Details
    ISSN: 1573-7055
    Keywords: DNA/DNA hybridization ; skull morphology ; molecular phylogeny ; Madagascar ; Cryptoprocta ; Carnivora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A molecular and morphological study of several living aeluroid Carnivora was completed to evaluate the evolutionary relationships of the endemicCryptoprocta ferox, a carnivore living on the island of Madagascar. The molecular analysis, based on DNA/DNA hybridization experiments, suggests thatCryptoprocta is more closely related to the Herpestidae (as represented byMungos andIchneumia) than it is to the Viverrinae (Genetta), Paradoxurinae (Paguma, Paradoxurus), Felidae (Felis, Panthera), or Hyaenidae (Crocuta). Based on bootstrapping procedures applied to the individual DNA/DNA results, three branching patterns were observed which differ only by the relative position of the Felidae within the Aeluroidea. The amounts of genetic divergence measured between pairs of compared taxa have been transformed into millions years datings by the molecular clock concept, and this was done by establishing a molecular time scale based on the fossil record of the aeluroid Carnivora.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01024706
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  • 3
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    Engineering applications of heuristic multilevel optimization methods (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Some engineering applications of heuristic multilevel optimization methods are presented and the discussion focuses on the dependency matrix that indicates the relationship between problem functions and variables. Coordination of the subproblem optimizations is shown to be typically achieved through the use of exact or approximate sensitivity analysis. Areas for further development are identified.
    Keywords: STRUCTURAL MECHANICS
    Type: Recent Advances in Multidisciplinary Analysis and Optimization, Part 3; p 1029-1037
    Format: application/pdf
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  • 4
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    Sensitivity analysis of flutter response of a typical section and a wing in transonic flow (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A sensitivity analysis of flutter response of a two-degree of freedom airfoil with plunging and pitching degrees of freedom in transonic flow was performed using a state-space representation of the unsteady aerodynamic behavior. The structural equations of motion of the airfoil with bending and torsional degrees of freedom are coupled to the unsteady airloads, and the aeroelastic system so modeled is solved as an eigenvalue problem to determine the stability. The results of eigenanalysis showed good agreement with flutter calculations performed using a time-integration of the aeroelastic equations. The sensitivities of the flutter speed with respect to the mass and stiffness parameters wee computed by both the analytical and finite difference methods, showing excellent agreement.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA PAPER 93-1646 , In: AIAA(ASME)ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 34th and AIAA/ASME Adaptive Structures Forum, La Jolla, CA, Apr. 19-22, 1993, Technical Papers. Pt. 5 (A93-33876 1; p. 2985-2997.
    Format: text
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  • 5
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    Sensitivity analysis of aeroelastic response of a wing using piecewise pressure representation (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A sensitivity analysis scheme of the static aeroelastic response of a wing is developed, by incorporating a piecewise panel-based pressure representation into an existing wing aeroelastic model to improve the model's fidelity, including the sensitivity of the wing static aeroelastic response with respect to various shape parameters. The new formulation is quite general and accepts any aerodynamics and structural analysis capability. A program is developed which combines the local sensitivities, such as the sensitivity of the stiffness matrix or the aerodynamic kernel matrix, into global sensitivity derivatives.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA PAPER 93-1645 , In: AIAA(ASME)ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 34th and AIAA/ASME Adaptive Structures Forum, La Jolla, CA, Apr. 19-22, 1993, Technical Papers. Pt. 5 (A93-33876 1; p. 2974-2984.
    Format: text
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  • 6
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    Distributed computer system enhances productivity for SRB joint optimization (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The Programming System for Structural Synthesis software package, which couples structural analysis and optimization, has been distributed over a network of work stations for use in Space Shuttle Solid Rocket Booster joint redesign optimization. Finite difference computing techniques were applied to the optimization gradients in parallel execution, allowing several work stations to simultaneously contribute to the problem's solution. An optimal joint shape was obtained which achieves minimum weight while keeping the gap between joints well closed and limiting structural stresses. The optimization cycle was reduced from two hours to one-half hour.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA PAPER 87-0835
    Format: text
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  • 7
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    Structural optimization of an alternate design for the Space Shuttle solid rocket booster field joint (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A structural optimization procedure is used to determine the shape of an alternate design for the Shuttle's solid rocket booster field joint. In contrast to the tang and clevis design of the existing joint, this alternate design consists of two flanges bolted together. Configurations with 150 studs of 1 1/8 in diameter and 135 studs of 1 3/16 in diameter are considered. Using a nonlinear programming procedure, the joint weight is minimized under constraints on either von Mises or maximum normal stresses, joint opening and geometry. The procedure solves the design problem by replacing it by a sequence of approximate (convex) subproblems; the pattern of contact between the joint halves is determined every few cycles by a nonlinear displacement analysis. The minimum weight design has 135 studs of 1 3/16 in diameter and is designed under constraints on normal stresses. It weighs 1144 lb per joint more than the current tang and clevis design.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA PAPER 87-0702
    Format: text
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  • 8
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    Updating finite element dynamic models using an element-by-element sensitivity methodology (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-08-14
    Description: A sensitivity-based methodology for improving the finite element model of a given structure using test modal data and a few sensors is presented. The proposed method searches for both the location and sources of the mass and stiffness errors and does not interfere with the theory behind the finite element model while correcting these errors. The updating algorithm is derived from the unconstrained minimization of the squared L sub 2 norms of the modal dynamic residuals via an iterative two-step staggered procedure. At each iteration, the measured mode shapes are first expanded assuming that the model is error free, then the model parameters are corrected assuming that the expanded mode shapes are exact. The numerical algorithm is implemented in an element-by-element fashion and is capable of 'zooming' on the detected error locations. Several simulation examples which demonstate the potential of the proposed methodology are discussed.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal (ISSN 0001-1452); 31; 9; p. 1702-1711.
    Format: text
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  • 9
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    Research in Structures, Structural Dynamics and Materials, 1990 (1990)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Structural Dynamics and Materials (SDM) Conference was held on April 2 to 4, 1990 in Long Beach, California. This publication is a compilation of presentations of the work-in-progress sessions and does not contain papers from the regular sessions since those papers are published by AIAA in the conference proceedings.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CP-3064 , L-16735 , NAS 1.55:3064 , Conference; Apr 02, 1990 - Apr 04, 1990; Long Beach, CA; United States
    Format: application/pdf
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