Observation of breathing-like modes in an individual multiwalled carbon nanotube

We study collective vibrational breathing modes in the Raman spectrum of a multiwalled carbon nanotube. In correlation with high-resolution transmission electron microscopy, we find that these modes have energies differing by more than 23% from the radial breathing modes of the corresponding single-walled nanotubes. This shift in energy is explained with intershell interactions using a model of coupled harmonic oscillators. The strength of this interaction is related to the coupling strength expected for few-layer graphene.     

Beurteilung des Ermüdungsverhaltens von Krankonstruktionen bei Einsatz hoch‐ und ultrahochfester Stähle

Analysis of fatigue details typically used in crane structures. For joints and attachments in crane structures usually the verification of the fatigue strength governs the design. When using the nominal stress approach some details often used in crane structures, especially welded details, cannot be classified according to the tables of fatigue classes given in the standards. Together with representatives from the crane industry such details have been identified. In the frame of the FOSTA research project P 512 fatigue tests have been carried out, so that proposals for the classification according to Eurocode 3 could be made. In addition, fatigue tests on structural details already covered by the codes have been executed to check the influence of material strength. A general increase of the fatigue strength when using high strength steel could not be observed but details with low notch effects show a better behaviour compared with normal strength steel. This is attributed to higher fabrication qualities. The research project P 512 was funded by the Stiftung Stahlanwendungsforschung, Essen, and has been carried out in behalf of the Forschungsvereinigung Stahlanwendung e.V.     

The Deep Structure of the Picturesque

The late Paul Coates was one of the first students at the Architectural Association (AA) in London to submit an international computation-based diploma, in 1969. Responsible for introducing a series of computational techniques, Coates was also the founder of the MSc in Computing and Design at the University of East London, and in 2002 the Centre for Evolutionary Computing in Architecture (CECA). In this unpublished article from 2008, which has been prepared and rewritten for publication by Christian Derix , Coates recounts his pursuit of ‘the particle physics of architecture’ - geometric rules that inform both unplanned and planned human occupation of space.     

Robust Empirical Predictions of Residual Performance of Damaged Composites with Quantified Uncertainties

Robust predictions with estimated uncertainties were made for the residual strength of impact-damaged composite laminates based on simple non-destructive measurements of the size of the damage from ultrasound C-scans. Experimental data was acquired for two sets of composite coupons, one with a crossply and the other with a quasi-isotropic layup. The laminates were subject to drop-weight impacts, non-destructively evaluated using ultrasound and then loaded to failure in bending. An empirical model of the residual strength of each laminate layup, as a function of the ultrasound measurements, was generated by fitting a Bayesian linear regression model to the normalised measured data. Bayesian linear regression was demonstrated to provide conservative estimates when only minimal data is available. Unlike classical regression, this technique provides a robust treatment of outliers, which avoids underestimation of residual strength. The Leave-One-Out-Cross-Validation (LOOCV) metric was used to assess the performance of models allowing for the quantitative comparison of the predictive power of regression models as well as being consistent in the presence of outliers in the data. The LOOCV metric indicated that predictions of residual strength are up to 25% more accurate when based on damage area than when using measurements of the damage width or length. The proposed approach provides a robust methodology for performing damage assessments in safety critical composite components based on reliable predictions with quantified uncertainties.     

Bibliometric analysis of the evolution of biochar research trends and scientific production

Clean Technologies and Environmental Policy - Biochar has caught great attention over the last decade, yielding a large number of publications in a broad range of disciplines. This scientometric...     

Tunable colors and conductivity by electroless growth of Cu/Cu2O particles on sol-gel modified cellulose

Nano Research - Development of colored surfaces by formation of nano-structured aggregates is a widely used strategy in nature to color lightweight structures (e.g. butterflies) without the use of...     

Evaluation of non-linear strain paths using Generalized Forming Limit Concept and a modification of the Time Dependent Evaluation Method

The prediction of formability is one of the most important tasks in sheet metal forming process simulation. The common criterion for ductile fracture in industrial applications is the Forming Limit Diagram (FLD). This is only applicable for linear strain paths. However, in most industrial simulation cases non-linear strain paths occur. To resolve this problem, a phenomenological approach is introduced, the so-called Generalized Forming Limit Concept (GFLC). The GFLC enables prediction of localized necking on arbitrary non-linear strain paths. Another possibility is the use of the Time Dependent Evaluation Method (TDEM) within the simulation as a failure criteria. During the Numisheet Benchmark 1 (2014) a two-stage forming process was performed with three typical sheet materials (AA5182, DP600 and TRIP 780) and three different blank shapes. The task was to determinate the point in time and space of local instability. Therefore the strain path for the point of maximum local thinning is evaluated. To predict the start of local necking the Generalized Forming Limit Concept (GFLC), the Time Dependent Evaluation Method (TDEM) and the modified TDEM were applied. The results of the simulation are compared with the results of the Benchmark experiment.