Cellulose as a binding material in graphitic anodes for Li ion batteries: a performance and degradation study

Four types of cellulose, in particular carboxy methyl cellulose (CMC), are tested as potential binding materials in graphitic anodes for lithium ion batteries. It is shown that a minimum content of a cellulose which gives acceptable anode properties (reversible capacity>300 mA h g⁻¹ during the first 10 cycles, irreversible loss<20%) is about 2 wt.%, which is less than in the case of conventional polymeric binders (5-10 wt.%). Kinetics of insertion-deinsertion and passivation processes seem not to be affected by the presence of cellulose. Explanation for the electrode failure at cellulose contents lower than 1 wt.% is given based on X-ray diffraction and microscopy investigations. Finally, the structure (distribution) of cellulose in the composite anode material is discussed and (indirectly) checked with a series of experiments. Most results are compared with the corresponding results obtained either with gelatin or conventional polymeric binders or both.     

Modelling the scatter of E–N curves using a serial hybrid neural network

If structural reliability is estimated by following a strain-based approach, a material’s strength should be represented by the scatter of the ε–N (E–N) curves that link the strain amplitude with the corresponding statistical distribution of the number of cycles-to-failure. The basic shape of the ε–N curve is usually modelled by the Coffin–Manson relationship. If a loading mean level also needs to be considered, the original Coffin–Manson relationship is modified to account for the non-zero mean level of the loading, which can be achieved by using a Smith–Watson–Topper modification of the original Coffin–Manson relationship. In this paper, a methodology for estimating the dependence of the statistical distribution of the number of cycles-to-failure on the Smith–Watson–Topper modification is presented. The statistical distribution of the number of cycles-to-failure was modelled with a two-parametric Weibull probability density function. The core of the presented methodology is represented by a multilayer perceptron neural network combined with the Weibull probability density function using a size parameter that follows the Smith–Watson–Topper analytical model. The article presents the theoretical background of the methodology and its application in the case of experimental fatigue data. The results show that it is possible to model ε–N curves and their scatter for different influential parameters, such as the specimen’s diameter and the testing temperature.     

Improving the performance of Federated Digital Library services

The number of Digital Libraries (DLs) accessible over the Open Archives Initiative–Protocol for Metadata Harvesting (OAI–PMH) has been constantly increasing in the past years. Earlier efforts in the DL area have concentrated on metadata harvesting and provisioning of value-added Federated Digital Library (FDL) services to the users. FDL services, however, have to meet significant performance and scalability requirements, which is difficult to achieve in centralized metadata harvesting systems. The goal of the present study was to evaluate the benefits of using Web Services Resource Framework (WSRF) compliant grid middleware infrastructure for providing efficient and reliable FDL services. The presented FDL application allows for parallel harvesting of OAI–PMH compliant DLs. The results show that this approach efficiently solves the performance related problems, while it also contributes to greater flexibility of the system. The quality of service is improved as metadata can be updated frequently, and the system does not exhibit a single point of failure.     

Do simultaneous inventions sleep? A case study on nursing sleeping papers

Simultaneous inventions and Sleeping papers are two interesting phenomena in scientific discovery and knowledge development processes, however they were not yet researched as a single occurrence. To close this gap, we performed a bibliometric study in which we analysed if simultaneous discoveries can also be subjected to delayed recognition. The analysis was performed on four already identified nursing Sleeping Papers and resulted in one Sleeping simultaneous invention. Sleeping simultaneous inventions or partially sleeping inventions may represent a valuable source for improved understanding about knowledge development processes and are worth candidates for future research.

     

Did Sleeping Papers in nursing research miss their target audience?

Scientometrics - Various factors have been attributed for delayed recognition of Sleeping Papers, for example introducing new technologies which didn’t yet exist, or proposing ideas that were...     

Theoretical framework for estimating a product's reliability using a variable‐amplitude loading spectrum and a stress‐based approach

An innovative approach for predicting the reliability of a structure that is subject to a variable‐amplitude dynamic load is presented. In this approach, a Gassner durability curve with its scatter is modelled using a 2‐parametric Weibull's probability density function (PDF). The trend of the Gassner durability curve is modelled with a general hyperbola equation in a log‐log scale. The hyperbola equation is applied to represent the durability curve for the 63.2% probability of fatigue failure that describes the dependency of the Weibull's scale parameter on the loading spectrum's maximum stress. Equations are derived to link the parameters of the hyperbola curve to the material's S‐N curve and the loading spectrum. The Weibull's shape parameter is estimated from the scatter of the material's S‐N curve. The proposed Gassner‐curve model is applied to calculate the fatigue reliability from the PDF of the loading spectrum's maximum stress and the PDF of the durability‐curve's amplitude stress for the selected number of loading‐cycles‐to‐failure.     

Dual representation of spatial rational Pythagorean-hodograph curves

In this paper, the dual representation of spatial parametric curves and its properties are studied. In particular, rational curves have a polynomial dual representation, which turns out to be both theoretically and computationally appropriate to tackle the main goal of the paper: spatial rational Pythagorean-hodograph curves (PH curves). The dual representation of a rational PH curve is generated here by a quaternion polynomial which defines the Euler–Rodrigues frame of a curve. Conditions which imply low degree dual form representation are considered in detail. In particular, a linear quaternion polynomial leads to cubic or reparameterized cubic polynomial PH curves. A quadratic quaternion polynomial generates a wider class of rational PH curves, and perhaps the most useful is the ten-parameter family of cubic rational PH curves, determined here in the closed form.