Influence of neural network training parameters on short-term wind forecasting

This paper investigates factors which can affect the accuracy of short-term wind speed prediction when done over long periods spanning different seasons. Two types of neural networks (NNs) are used to forecast power generated via specific horizontal axis wind turbines. Meteorological data used are for a specific Western Australian location. Results reveal that seasonal variations affect the prediction accuracy of the wind resource, but the magnitude of this influence strongly depends on the details of the NN deployed. Factors investigated include the span of the time series needed to initially train the networks, the temporal resolution of these data, the length of training pattern within the overall span which is used to implement the predictions and whether the inclusion of solar irradiance data can appreciably affect wind speed prediction accuracy. There appears to be a relatively complex relationship between these factors and the accuracy of wind speed prediction via NNs. Predicting wind speed based on NNs trained using wind speed and solar irradiance data also increases the prediction accuracy of wind power generated, as can the type of network selected.     

Quality and consumer acceptance of radio frequency and traditional heat pasteurised kiwi puree during storage

To explore the feasibility of using radio frequency (RF) heating as a method to process kiwi puree, this study compared the effects of RF heating with traditional heat pasteurisation (TP) on various properties of kiwi puree. RF treatment completely inactivate of microbes in kiwi puree, with total aerobic bacteria counts (TAC) decreased by 4.81 log CFU mL^?1 and yeast and mould counts (YMC) decreased by 2.62 log CFU mL^?1, which are similar to TP treatment. During the 7 weeks’ storage, RF‐treated puree showed retarded growth of microbes. The pH, titratable acidity and °Brix values of RF‐treated samples were significantly different from those of the control. The vitamin C, total phenolic compounds and antioxidant capacity of RF‐treated samples were significantly higher than those of TP‐treated samples during storage. RF‐treated sample retained better colour than TP‐treated sample throughout storage. The customer satisfaction analysis indicated that consumers prefer RF‐treated kiwi puree than TP‐treated samples. These findings suggest that RF heating has potential applications in processing of kiwi puree or similar products.     

Near-infrared spectroscopy coupled chemometric algorithms for prediction of antioxidant activity of black goji berries (<Emphasis Type="Italic">Lycium ruthenicum</Emphasis> Murr.)

In this study, near-infrared (NIR) spectroscopy coupled with partial least-squares (PLS) regression and various efficient variable selection algorithms, synergy interval-PLS (Si-PLS), backward interval PLS (Bi-PLS) and genetic algorithm-PLS (GA-PLS) were applied comparatively for the prediction of antioxidant activity in black wolfberry (BW). The eight assays were used for quantification of antioxidant content. The developed models were assessed using correlation coefficients (R²) of the calibration (Cal.) and prediction (Pre.); root mean square error of prediction, RMSEP; standard Error of Cross-Validation, RMSECV and residual predictive deviation, RPD. The performance of the built model greatly improved by the application of Si-PLS, Bi-PLS and GA-PLS compared with full spectrum PLS. The R² values determined for calibration and prediction set ranged from 0.8479 to 0.9696 and 0.8401 to 0.9638, respectively. These findings revealed that NIR spectroscopy combined with chemometric algorithms can be used for quantification of antioxidant activity in BW samples.     

Herausforderungen &amp; Wichtigkeit der Korrosionsprüfung an automobilen Abgassystemanlagen

Standard corrosion test methods are largely known in the automotive supplier industry and are among the common tests. Different tests, like salt spray testing as well as combined-alternating tests in climatic chambers, are commonly used to evaluate the corrosion behavior of stainless steels. Corrosion effects like uniform and pitting corrosion can be simulated and quantified, and thus base materials can be separated according to their corrosion performance. Still, the correlation to reality and the behavior in the field are still an open question. Respecting the wide range of exhaust applications, especially the influence of temperature, the technical requirements have been greatly increased in the last years and the corrosion effects are difficult to replicate. In addition, the target lifetime for exhaust systems are increasing more and more.Within the scope of a project group at FAURECIA CLEAN MOBILITY, a concept has been developed with the target to combine the common corrosion testing with application oriented component tests. The objective is to cover the time-temperature influence on the corrosion behavior of a component in one test. A testing device has been developed which combines all the technical requirements in one test under elevated temperature influence to make estimations about lifetime, design, and material selections.     

The development of novel auxetic woven structure for impact applications

Nowadays, the auxetic materials, auxetic reinforcement as well as auxetic composite are under the great attention of scientific research due to having excellent mechanical properties. In the current research work, the impact resistance of composite was improved by modifying the four layer through the thickness woven structure, that was used as reinforcement. A comparison was made between the standard four layer through the thickness and modified four layer through the thickness woven structure in terms of auxeticity and penetration. The modified four layer through the thickness woven structure showed auxetic behavior in both warp and weft direction having less penetration resistance as compared to standard sample. The four layer through the thickness non-auxetic woven structures and modified auxetic four layer thorough the thickness woven structures were used as reinforcements to develop composite for impact resistance comparison. The result showed that impact resistance of auxetic composite was 6.7% greater as compared to the non-auxetic composite. It was concluded that the greater value of impact resistance was due to the auxetic behavior of modified four layer through the thickness woven structure.     

Multi-response optimization of mechanical and comfort properties of bi-stretch woven fabrics using grey relational analysis in Taguchi method

The present paper envisages the multi-response optimization of certain factors like elastane linear density, fabric thread density and weave float on some mechanical, (i.e. stretch %, recovery %) and comfort (i.e. air permeability) properties of bi-stretch woven fabrics, under L₁₈ orthogonal array in Taguchi design. Fabric samples were produced using elastane core-spun cotton yarns both in the warp and weft. The elastane linear density, fabric thread density and weave float size were used as predictor variables, while fabric air permeability, stretch and recovery were taken as response variables. Two different elastane linear densities, i.e. 44 dtex and 78 dtex, 3 different thread densities and 3 different weave designs, i.e. 1/1 plain, 2/2 z-twill and 3/3 z-twill were used. The results have been analysed using grey relational analysis for the identification of an optimum level of process factors. Furthermore, using analysis of variance method, significant contributions of predictor variables were determined.     

Development and characterization of jute/polypropylene composite by using comingled nonwoven structures

High melt viscosity of thermoplastic matrices hinders the impregnation of fibers and their consolidation during fabrication of composites. In the present study, matrix (polypropylene) and reinforcement (jute) fibers were comingled at fiber to fiber level (fiber to matrix ratio of 30, 40, 50 and 60%) while making their nonwoven fabrics using dry laid process. Thermoforming process, in which polypropylene fibers are used and then melted for the development of composite plates. The results showed that the composite samples with 0.30 fiber volume fraction have higher mechanical properties (flexural, impact energy), while samples with 0.40 fiber volume fraction have higher tensile properties (tensile strength and modulus) due to good impregnation of fiber and better fiber-matrix interface. The composite having 0.30 fiber volume fraction has lowest value of moisture regain and diffusion coefficients than the other samples. Voids present in the microscopic images also confirmed the weak interface, when the fiber volume fraction increased up to 0.60.     

Effect of As,Cu and Sb impurities on performance of Pb‐Ca‐Sn grids of lead‐acid batteries

The performance of Pb‐Ca‐Sn grids of lead‐acid batteries made from recycled lead in 4 M H₂SO₄ in the absence and presence of traces of Cu, As and Sb, as potential impurities in the recycling process at 0.1% level, is investigated by electrochemical methods. The study includes the effect of each impurity and impurities combined on the alloy corrodibility, the efficiency of PbO₂ formation, the rate of the self‐discharge and the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). The results show that individual impurity enhances the corrosion resistance but increases the anode corrosion and the self‐discharge rate. Impurities play opposite effects on hydrogen evolution reaction and oxygen evolution reaction either individually or combined. Concerning water loss problem, the harmful effect of individual impurity on increasing oxygen evolution reaction is compensated by their suppression of hydrogen evolution reaction. The impurities combined suppress effectively both hydrogen evolution reaction and oxygen evolution reaction relative to alloy without any impurity. Sb has the highest harmful effects on oxygen evolution reaction and the self‐discharge but it is the best in the suppression of hydrogen evolution reaction. The impurities combined relatively improve the general corrosion resistance, the anode corrosion resistance and the self‐discharge. The study supports higher tolerance levels of Cu, As and Sb in Pb‐Ca‐Sn grids, especially when present combined, than the recommended levels in the industry standards.     

Exponential localization of moving end mirror in optomechanics

We discuss the dynamics of moving end mirror of an optomechanical system that consists of a Fabry-Perot cavity loaded with dilute condensate and driven by a single-mode optical field. It is shown that quantum mechanical phenomenon of dynamical localization occurs both in position and momentum space for moving end mirror in the system. The parametric dependencies of dynamical localization are discussed. We also provide a set of parameters which makes this phenomenon experimentally feasible.