Effect of sampling on real ocular aberration measurements

The minimum number of samples necessary to fully characterize the aberration pattern of the eye is a question under debate in the clinical as well as the scientific community. We performed repeated measurements of ocular aberrations in 12 healthy nonsurgical human eyes and in 3 artificial eyes, using different sampling patterns (hexagonal, circular, and rectangular with 19 to 177 samples, and 3 radial patterns with 49 sample coordinates corresponding to zeros of the Albrecht, Jacobi, and Legendre functions). For each measurement set we computed two different metrics based on the root-mean-square (RMS) of difference maps (RMS_Diff) and the proportional change in the wavefront (W%). These metrics are used to compare wavefront estimates as well as to summarize results across eyes. We used computer simulations to extend our results to "abnormal eyes" (keratoconic, post-LASIK, and post-radial keratotomy eyes). We found that the spatial distribution of the samples can be more important than the number of samples for both our measured as well as our simulated "abnormal" eyes. Experimentally, we did not find large differences across patterns except, as expected, for undersampled patterns.     

Dynamic in situ observation of rapid size and shape change of supported Pd nanoparticles during CO/NO cycling

Understanding and improving the behaviour of supported precious-metal catalysts for a vast array of environmentally and economically important processes is a central area of research in catalysis. The removal of toxic gases such as CO and NO, without forming others (such as N(2)O), is particularly important. By combining energy-dispersive extended X-ray absorption fine-structure spectroscopy with a vibrational spectroscopy (infrared) and mass spectrometry, at high time resolution, in a single in situ experiment, we dynamically observe and quantify CO-, and subsequent NO-, induced size and shape changes of Pd nanoparticles during CO/NO cycling. In doing so we demonstrate a novel, non-oxidative redispersion (for example, an increase in metal surface area) mechanism, and suggest a model to bridge the structural and reactive functions of supported Pd catalysts.     

Development of a patterning system for vitrified CBN wheels based on modal analysis

One of the alternatives under development by industry to reduce tailpipe emissions in internal combustion engines is the texturing of the crankshaft bearings using patterned grinding wheels. As modern industrial grinding solutions for forged crankshafts are based on vitrified CBN wheels, a new approach is needed for rotary dressing patterning. This paper describes the development of patterning system for vitrified CBN wheels based on modal vibration analysis. Aspects related to the device design, modelling and simulation of the texturing process are discussed in the paper. The obtained results reported in this paper indicate a high potential for industrial application.     

Local order scheduling for mixed-model assembly lines in the aircraft manufacturing industry

Multi-variant products to be assembled on mixed-model assembly lines at locations within a production network need to be scheduled locally. Scheduling is a highly complex task especially if it simultaneously covers the assignment of orders, which are product variants to be assembled within a production period, to assembly lines as well as their sequencing on the lines. However, this is required if workers can flexibly fulfill tasks across stations of several lines and, thus, capacity of workers is shared among the lines. As this is the case for final assembly of the Airbus A320 Family, this paper introduces an optimization model for local order scheduling for mixed-model assembly lines covering both assignment to lines as well as sequencing. The model integrates the planning approaches mixed-model sequencing and level scheduling in order to minimize work overload in final assembly and to level material demand with regard to suppliers. The presented model is validated in the industrial application of the final assembly of the Airbus A320 Family. The results demonstrate significant improvement in terms of less work overload and a more even material demand compared to current planning.     

Predictive quality control of hybrid metal-CFRP components using information fusion

The paper presents an approach to determine the durability of hybrid metal-CFRP components combining the results of non-destructive testing (ndt) and finite element simulation The advantage of hybrid metal-CFRP components lies in the use of the properties of the materials used. CFRP parts with higher specific stiffness and strength are combined with metallic joining points, so that established joining processes for metal components can be applied to these lightweight components. In order to further promote the use of these hybrids in industry, it is necessary to guarantee a high level of component reliability through 100% quality control in order to avoid production-related defects. These defects such as delamination or fibre disorientation however vary in shape, size and position and lead to different effects on the part performance and reliability. Therefore the presented approach includes the application of non-destructive testing methods that are applied as in-line quality control measures in order to determine defect characteristics of the inspected parts. Due to the novelty of the component under test it is necessary to evaluate the individual criticality of detected defects and how they affect part performance during the testing procedure. Therefore the acquired ndt-data is used in finite element simulations where defect characteristics are added to the component model and whose effects on part reliability are evaluated. The generation of additional information combining non-destructive testing and simulation is referred to as data fusion. In order to evaluate the validity of the presented approach the determined part performances are compared to experimental mechanic tests.     

Modeling the spread of COVID-19 in New York City

This paper proposes an ensemble predictor for the weekly increase in the number of confirmed COVID-19 cases in the city of New York at zip code level. Within a Bayesian model averaging framework, the baseline is a Poisson regression for count data. The set of covariates includes autoregressive terms, spatial effects, and demographic and socioeconomic variables. Our results for the second wave of the coronavirus pandemic show that these regressors are more significant to predict the number of new confirmed cases as the pandemic unfolds. Both pointwise and interval forecasts exhibit strong predictive ability in-sample and out-of-sample.     

$${ SIM}^2{ RRAM}$$: a physical model for RRAM devices simulation

In the last few years, resistive random access memory (RRAM) has been proposed as one of the most promising candidates to overcome the current Flash technology in the market of non-volatile memories. These devices have the ability to change their resistance state in a reversible and controlled way applying an external voltage. In this way, the resulting high- and low-resistance states allow the electrical representation of the binary states “0” and “1” without storing charge. Many physical models have been developed with the aim of understanding the mechanisms that control the resistive switching. In this work, we have compiled the main theories accepted as well as their corresponding models for the conduction characteristics. In addition, simulation tools play a very important role in the task of checking these theories and understanding these mechanisms. For this reason, the simulation tool called \(\hbox {SIM}^{2}\hbox {RRAM}\) has been presented. This simulator is capable of replicating the global behavior of RRAM cell based on \(\hbox {HfO}_{x}\).     

Microchannel emulsification: A promising technique towards encapsulation of functional compounds

ABSTRACT

This review provides an overview of microchannel emulsification (MCE) for production of functional monodispersed emulsion droplets. The main emphasis has been put on functional bioactives encapsulation using grooved-type and straight-through microchannel array plates. MCE successfully encapsulates the bioactives like β-carotene, oleuropein, γ-oryzanol, β-sitosterol, L-ascorbic acid and ascorbic acid derivatives, vitamin D and quercetin. These bioactives were encapsulated in a variety of delivery systems like simple and multiple emulsions, polymeric particles, microgels, solid lipid particles and functional vesicles. The droplet generation process in MCE is based upon spontaneous transformation of interfaces rather than high energy shear stress systems. The scale-up of MCE can increase the productivity of monodispersed droplets >100 L h^?1 and makes it a promising tool at industrial level.     

Oven‐dried table olives: textural properties as related to pectic composition

The effects of processing treatments on the microscopic structure, pectic fractions and firmness of ripe olives (Olea europaea L Cassanese variety), processed by the ‘Ferrandina’ method for oven‐dried table olive production, were studied. The process included a first heating step, a salting step and a final oven‐drying process. Scanning electron microscopic observations of olive tissue structure revealed that heat treatment was highly damaging, affecting the intercellular pectic substances and producing cell separation. Epicuticular waxes were barely affected and limited the shrivelling of the fruit during the oven dehydration process. The pectin content was higher in the oven‐dried olives than in the fresh samples. The sodium hydroxide‐soluble fraction was the main pectin fraction in the olive tissues. Its content decreased markedly after the heating step, while it increased after the oven dehydration step. The softening of the olive tissues increased after heat treatment, and a correlation was found between protopectin content and firmness. In oven‐dried olives a firming of the olive tissues was observed due to the de‐esterification of pectin and to its decreased solubility resulting from an increase in cell wall calcium bridging. © 2000 Society of Chemical Industry