Magnetostrictive sensors for composite damage detection and wireless structural health monitoring

The efficacy of magnetostrictive ribbon actuators as aerospace composites impact damage detectors has been investigated through finite-element modeling and experimental studies, investigating both the sensitivity of magnetostrictive ribbons embedded and surface mounted using the tensile and three-point bending tests. From the modeling, it was found that the surface-mounted ribbons increased Young's modulus of the system compared to the composite alone but caused the ribbons to delaminate from the surface before failure. The embedded ribbons did not appear to affect the structural properties of the composite, which was observed through the three-point bending tests carried out. From the impact damage tests, it was determined that the ribbons had to be embedded two-ply below the surface to measure impact energies greater than 1.6 J. For surface-mounted ribbons, damages of 1.6 J to the surface could be detected and pinpointed for two ribbons 10 mm apart. We also demonstrate in a simple way how a two-ribbon scheme may be used to determine the damage position in the tested sample, which may be extended for wireless sensing

The integrated microbial genomes (IMG) system

The integrated microbial genomes (IMG) system is a new data management and analysis platform for microbial genomes provided by the Joint Genome Institute (JGI). IMG contains both draft and complete JGI genomes integrated with other publicly available microbial genomes of all three domains of life. IMG provides tools and viewers for analyzing genomes, genes and functions, individually or in a comparative context. IMG allows users to focus their analysis on subsets of genes and genomes of interest and to save the results of their analysis. IMG is available at

Removal of non-CO2 greenhouse gases by large-scale atmospheric solar photocatalysis

Large-scale atmospheric removal of greenhouse gases (GHGs) including methane, nitrous oxide and ozone-depleting halocarbons could reduce global warming more quickly than atmospheric removal of CO2. Photocatalysis of methane oxidizes it to CO2, effectively reducing its global warming potential (GWP) by at least 90%. Nitrous oxide can be reduced to nitrogen and oxygen by photocatalysis; meanwhile halocarbons can be mineralized by red-ox photocatalytic reactions to acid halides and CO2. Photocatalysis avoids the need for capture and sequestration of these atmospheric components. Here review an unusual hybrid device combining photocatalysis with carbon-free electricity with no-intermittency based on the solar updraft chimney. Then we review experimental evidence regarding photocatalytic transformations of non-CO2 GHGs. We propose to combine TiO2-photocatalysis with solar chimney power plants (SCPPs) to cleanse the atmosphere of non-CO2 GHGs. Worldwide installation of 50,000 SCPPs, each of capacity 200 MW, would generate a cumulative 34 PWh of renewable electricity by 2050, taking into account construction time. These SCPPs equipped with photocatalyst would process 1 atmospheric volume each 14–16 years, reducing or stopping the atmospheric growth rate of the non-CO2 GHGs and progressively reducing their atmospheric concentrations. Removal of methane, as compared to other GHGs, has enhanced efficacy in reducing radiative forcing because it liberates more °OH radicals to accelerate the cleaning of the troposphere. The overall reduction in non-CO2 GHG concentration would help to limit global temperature rise. By physically linking greenhouse gas removal to renewable electricity generation, the hybrid concept would avoid the moral hazard associated with most other climate engineering proposals

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Thermal oscillations in a single channel upflow boiling system

Investigations on three two-phase flow instability phenomena--namely, thermal and pressure-drop oscillations and Ledinegg instability--are presented.In the first part of the dissertation, the experimental set-up and experimental procedure are described. Some typical results for steady-state pressure-drop versus mass flow rate characteristics and the pressure-drop and thermal oscillations are presented and discussed. A scaling analysis for the period of the thermal and pressure-drop oscillations is performed, and it is shown that the scale of the period can be represented as a simple function of the surge-tank (compressible) volume and operating mass flow rate.Next, details of finite-difference analysis of the oscillations are presented. The one-dimensional partial differential equations of the drift-flux model are solved for predicting steady-state characteristics, and reasonably good results are obtained. The pressure-drop and thermal oscillations are simulated by making use of the steady-state results and a quasi-steady-state approximation. Good agreement between the theory and experiments is shown.In the third part of the thesis, some analytical results are derived for pressure-drop oscillations and the Ledinegg instability. An integral model is developed, which results in a three-dimensional, nonlinear, coupled set of ordinary differential equations. Predictions of this simple model about the behavior of the system are in good agreement with experimental results. Also, correct parametric behavior with respect to the compressible volume and the mass flow rate is exhibited.A bifurcation analysis is carried out next, and it is shown that the pressure-drop oscillation limit-cycles are a consequence of a super-critical Hopf bifurcation that takes place in the dynamics of the system as heat input is increased. It is also shown that the Ledinegg instability is a result of a saddle-node bifurcation, which occurs with further addition of heat. Thus, these two instability mechanisms are treated on a common ground. Finally, the bifurcation set for the two-phase flow system is developed, and all possible behaviors of the system are outlined.</p