Analysis of indeterminate structures by combining redundants

Call number: LD2668 .R4 1964 D23

Three-Dimensional Finite Element Analysis of Composite Laminates Subjected to Transverse Impact

An interest in the low velocity impact probkins has been revived with the advent of laminated composite materials and their increasing use in aerospace and other applications. The reason for this new activity is that despite certain advantages of these materials over more traditional materials, composites are known to be vulnerable to impact. Impacts may occur anywhere during manufacture, normal operations,or maintenance and may induce significant internal damage in the form of matrix cracking, delarnination or fibre breakage, that are undetectable by visual inspection and cause significant reductions in the strength and stability of the structure. In the present paper. a three-dimensional finite element and transient dynamic analysis of fibre-reinforced polymer matrix composite laminates (e.g. graphite/epoxy, glass/epoxy, etc.) subjected to transverse foreign object impact is performed. Layered version of eight-noded isoparametric brick element with incompatible modes is used to model the laminate. Transient dynamic equilibrium equation is integrated step-by-step with respect to time using Newmark direct time integration method. Non-linear contact law reported in literature is used to model the local contact behavior and the timevartiing contact force is calculated based on the relative displacement between impactor and laminate using Newton-Raphson method. Based on the finite element model, a versatile computer software was developed in C++ programming language using object- oriented approach. The software can be used to determine several results such as contact force history, displacement and velocity histories of impactor and the timevarying displacements, forces, strains and stresses throughout the laminate. Some example problems are considered to study the effects of impactor velocity and laminate boundary conditions on impact behavior of graphite/epoxy composite laminates, and results are presented for time-history of contact force and laminate central deflection.The transient dynamic strains and stresses inside the laminate were also calculated for few case

Effects of non-universal large scales on conditional structure functions in turbulence

We report measurements of conditional Eulerian and Lagrangian structure functions in order to assess the effects of non-universal properties of the large scales on the small scales in turbulence. We study a 1m $\times$ 1m $\times$ 1.5m flow between oscillating grids which produces $R_\lambda=285$ while containing regions of nearly homogeneous and highly inhomogeneous turbulence. Large data sets of three-dimensional tracer particle velocities have been collected using stereoscopic high speed cameras with real-time image compression technology. Eulerian and Lagrangian structure functions are measured in both homogeneous and inhomogeneous regions of the flow. We condition the structure functions on the instantaneous large scale velocity or on the grid phase. At all scales, the structure functions depend strongly on the large scale velocity, but are independent of the grid phase. We see clear signatures of inhomogeneity near the oscillating grids, but even in the homogeneous region in the center we see a surprisingly strong dependence on the large scale velocity that remains at all scales. Previous work has shown that similar correlations extend to very high Reynolds numbers. Comprehensive measurements of these effects in a laboratory flow provide a powerful tool for assessing the effects of shear, inhomogeneity and intermittency of the large scales on the small scales in turbulence

Phytochemical screening and evaluation of antiulcer activity of ethanolic extract of Spathodea campanulata leaves

Peptic disorders like Gastroesophageal reflux disease, gastritis, peptic ulcer, duodenal ulcer, etc., are the common in today’s life style. This may be due to stressful life style or improper balance diet. The pathology behind these disorders may be discrepancy between offensive and defensive mechanisms either by excess secretion of acid and pepsin or diminished ability of the gastro-duodenal mucosal barrier to protect against stomach acid-pepsin secretion. Non-steroidal anti-inflammatory drugs (NSAIDs) are a class of the most commonly used medicines and proven to be effective for certain disorders. Some people use NSAIDs on daily basis for preventive purpose. But a variety of severe side effects can be induced by NSAIDs. Studies have shown that edible natural ingredients exhibit preventive benefit of gastric ulcer. Therefore present study was designed to evaluate antiulcer activity of ethanolic extract of Spathodea campanulata (S. campanulata) leaves in rats. Qualitative analysis of various phytochemical constituents was determined by the well-known test protocol available in the literature. The in vivo anti-ulcer activity of ethanolic extract was assessed against aspirin-induced gastric ulcer in rats. Depending on the model, outcome measures were volume and pH of gastric fluid, free acidity, total acidity and ulcer index as well as percent inhibition of ulcer index. Preliminary phytochemical screening revealed the presence of carbohydrates, glycosides, alkaloids, flavonoids, phenols & tannins, saponin. Further ethanolic extract of 200 and 400mg/ kg /p.o reduced the gastric volume, pH, ulcer number, ulcer index, free acidity and total acidity in aspirin induced ulcer models in rats. The findings of this study confirmed that S. campanulata extract has anti-ulcer pharmacologic activity due to one or more of the secondary metabolites present in it. Therefore, this study validates its anti-ulcer use in Indian folk medicine. Further investigations on isolation of specific phytochemicals and elucidating mechanisms of action are needed. Keywords: Spathodea campanulata, Phytochemical constituents, Antiulcer, Non-steroidal anti-inflammatory drugs, Aspirin-induced gastric ulcer

1997 NASA-ODU American Society for Engineering Education (ASEE) Summer Faculty Fellowship Program

Since 1964, the National Aeronautics and Space Administration (NASA) has supported a program of summer faculty fellowships for engineering and science educators. In a series of collaborations between NASA research and development centers and nearby universities, engineering faculty members spend 10 weeks working with professional peers on research. The Summer Faculty Program Committee of the American Society for Engineering Education supervises the programs. Objectives of the program are as follows: (1) To further the professional knowledge of qualified engineering and science faculty members, (2) To stimulate and exchange ideas between participants and NASA; (3) To enrich and refresh the research and teaching activities of participants' institutions; and (4) To contribute to the research objectives of the NASA center. Program description is as follows: College or university faculty members will be appointed as Research Fellows to spend 10 weeks in cooperative research and study at the NASA Langley Research Center. The Fellow will devote approximately 90 percent of the time to a research problem and the remaining time to a study program. The study program will consist of lectures and seminars on topics of interest or that are directly relevant to the Fellows' research topics. The lectures and seminar leaders will be distinguished scientists and engineers from NASA, education, and industry

The 1995 NASA-ODU American Society for Engineering Education (ASEE) Summer Faculty Fellowship Program

Since 1964, the National Aeronautics and Space Administration (NASA) has supported a program of summer faculty fellowships for engineering and science educators. In a series of collaborations between NASA research and development centers and nearby universities, engineering faculty members spend 10 weeks working with professional peers on research. The Summer Faculty Program Committee of the American Society for Engineering Education supervises the programs. The objectives of this program are: (1) To further the professional knowledge of qualified engineering and science faculty members; (2) To stimulate and exchange ideas between participants and NASA; (3) To enrich and refresh the research and teaching activities of participants' institutions; and (4) To contribute to the research objectives of the NASA center. College or university faculty members will be appointed as Research Fellows to spend 10 weeks in cooperative research and study at the NASA Langley Research Center. The Fellow will devote approximately 90 percent of the time to a research problem and the remaining time to a study program. The study program will consist of lectures and seminars on topics of interest or that are directly relevant to the Fellows' research topics. The lectures and seminar leaders will be distinguished scientists and engineers from NASA, education, or industry

The 1993 NASA-ODU American Society for Engineering Education (ASEE) Summer Faculty Fellowship Program

Since 1964, the National Aeronautics and Space Administration has supported a program of summer faculty fellowships for engineering and science educators. In a series of collaborations between NASA research and development centers and nearby universities, engineering faculty members spend 10 weeks working with professional peers on research. The Summer Faculty Program Committee of the American Society for Engineering Education supervises the programs. Objectives are: to further the professional knowledge of qualified engineering and science faculty members; to stimulate and exchange ideas between participants and NASA; to enrich and refresh the research and teaching activities of participants' institutions; and to contribute to the research objectives of the NASA center

Instability in Rice Production in Gujarat: A Decomposition Analysis

Rice is the most important and extensively grown food crop in India and is the staple food for more than half of the world population. In India, Gujarat ranks 15th in terms of area and production and 9th in productivity (2011). The scope for expanding rice production lies in enhancing productivity. The growth rates of rice area, production and productivity during 1982-83 to 2011-12 were 0.41, 1.25 and 0.83 percent per annum respectively. The growth estimate from last 30 years data shows that negligible increase was recorded in area and production of rice. Presently the yield level of rice in the state is comparatively low from national average need to be increased substantially. The magnitude of instability in area and production of rice has been higher in all the selected districts compared to state. Variability in production has been at a higher rate compared to area and productivity variability in this crop. The area-yield co-variance had a stabilizing effect on reduction of instability in rice production It can be inferred that the wide fluctuation in production of rice crop have been due to the high variability in its productivity. The future development programmes should envisage on increase of yield for bringing stabilization in production of the crop. The area instability also needs to be reduced. This could be reduced by more investment on research for rice production technology in the state