Analytical and Mathematical Analysis of the Vibration of Structural Systems Considering Geometric Stiffness and Viscoelasticity

For a complete analysis of vibration, the stiffness of a structure must have two characteristics: one corresponding to conventional stiffness and the other to the geometric stiffness. Thus, the total stiffness takes form where the model to be used to represent any behavior of the material is introduced to the first part via the modulus of elasticity. The second is the geometric stiffness, through which it is possible to linearize a geometric nonlinear problem. To consider both aspects, a mathematical model based on the Rayleigh method has been elaborated. Two systems were numerically studied. First, the occurrence of resonance in the vibration of a prestressed reinforced concrete beam has been investigated. The results indicated resonant and non-resonant schemes between the natural frequency of the beam and the frequency of the engine. To the second system, the first natural frequency of a slender, 40-m-high concrete mobile phone mast, was calculated, and an evaluation of the structural collapse was performed. To the both systems, the cross section of reinforced concrete was treated by the theory for the homogenized section in order to consider the presence of the steel, and the viscoelasticity of the concrete was taken into account through a three-parameter rheological model

United States Geological Survey Reports

From abstract: The Jarvis Creek coal field lies on the north side of the Alaska Range, between latitudes 63 35' and 63*45' N., and longitudes 145*40' and 145*50' W. It is 3 to 6 miles east of the Richardson Highway. The coal field is about 16 square miles in area, the major part of which is a rolling plateau that slopes gently northward and is bounded on the east, south. and west by bluffs facing Jarvis Creek, Ruby Creek, and the Delta River

‘CLAMP Online’: a new web-based palaeoclimate tool and its application to the terrestrial Paleogene and Neogene of North America

CLAMP Online is a new form-driven web facility enabling Climate Leaf Analysis Multivariate Program (CLAMP) palaeoclimate determinations to be conducted in their entirety without the need for additional software. This facility is demonstrated using physiognomic data from 82 Eocene to Pliocene fossil sites in North America, the Physg3brc CLAMP calibration file, and both locally derived climate data (Met3br) and 0.5° × 0.5° gridded climate data (GRIDMet3br). All the fossil sites fall within the physiog- nomic space defined by the Physg3brc dataset showing the versatility of this calibration for Paleogene to Present sites in North America. The fossil sites also plot in the mesic part of physiognomic space confirming that the source of the fossil material was vegetation growing under conditions where water was not growth-limiting to any significant degree. Regression equations are derived relating the local to the gridded climate predictions showing the relative predictive capabilities of each dataset, as well as offering ways to convert previously published data between the two calibrations. Palaeoclimate data (mean annual, warm month mean and cold month mean temperatures, growing season length, growing season and mean monthly growing season precipitation, precipitation during the three consecutive wettest and three consecutive driest months, and annual averages for relative and specific humidities and enthalpy) are given for all 82 sites