Hierarchical cellular designs for load-bearing biocomposite beams and plates

Scrutiny into the composition of natural, or biological materials convincingly reveals that high material and structural efficiency can be attained, even with moderate-quality constituents, by hierarchical topologies, i.e., successively organized material levels or layers. The present study demonstrates that biologically inspired hierarchical designs can help improve the moderate properties of natural fiber polymer composites or biocomposites and allow them to compete with conventional materials for load-bearing applications. An overview of the mechanics concepts that allow hierarchical designs to achieve higher performance is presented, followed by observation and results from flexural tests on periodic and hierarchical cellular beams and plates made from industrial hemp fibers and unsaturated polyester resin biocomposites. The experimental data is shown to agree well with performance indices predicted by mechanics models. A procedure for the multi-scale integrated material/structural analysis of hierarchical cellular biocomposite components is presented and its advantages and limitations are discussed.     

The evolution of the existing carrier infrastructure

With the continuing explosion in data traffic, incumbent carriers have several alternatives in attempting to meet this demand. Carriers can either replace, overlay, or migrate their networks, and only a migration strategy provides a cost-effective and manageable solution     

Round-Trip Prototyping Based on Integrated Functional and User Interface Requirements Specifications

Requirements engineering in the new millennium is facing an increasing diversity of computerised devices comprising an increasing diversity of interaction styles for an increasing diversity of user groups. Thus the incorporation of user interface requirements into software requirements specifications becomes more and more mandatory. Validating these requirements specifications with hand-made, throw-away prototypes is not only expensive, but also bears the danger that validation results are not accurately fed back into the requirements specification. In this paper, we propose an enhancement of the requirements specification method SCORES for an explicit capturing of user interface requirements. The advantages of the approach are threefold. First, the user interface requirements specification is UML-compliant and integrated into the functional requirements specification. Second, prototypes for validation purposes can semi-automatically be generated. Third, the model-based generation of prototypes allows for ‘round-trip prototyping’ such that manual changes of the prototype during the validation process are automatically fed back into the requirements specification.     

Thin-film optical function acquisition from experimental measurements of the reflectance and transmittance spectra: a case study

Journal of Materials Science: Materials in Electronics - The determination of the spectral dependence of thin-film optical functions from experimental measurements of the optical response,...     

Optimized Convolutional Neural Network Models for Skin Lesion Classification

Skin cancer is one of the most severe diseases, and medical imaging is among the main tools for cancer diagnosis. The images provide information on the evolutionary stage, size, and location of tumor lesions. This paper focuses on the classification of skin lesion images considering a framework of four experiments to analyze the classification performance of Convolutional Neural Networks (CNNs) in distinguishing different skin lesions. The CNNs are based on transfer learning, taking advantage of ImageNet weights. Accordingly, in each experiment, different workflow stages are tested, including data augmentation and fine-tuning optimization. Three CNN models based on DenseNet-201, Inception-ResNet-V2, and Inception-V3 are proposed and compared using the HAM10000 dataset. The results obtained by the three models demonstrate accuracies of 98%, 97%, and 96%, respectively. Finally, the best model is tested on the ISIC 2019 dataset showing an accuracy of 93%. The proposed methodology using CNN represents a helpful tool to accurately diagnose skin cancer disease.     

Identifying subassemblies and understanding their functions during a design review in immersive and non-immersive virtual environments

Design review (DR) is a product development (PD) activity used to inspect the technical characteristics of a design solution. Immersive virtual reality (IVR) technology enables the presentation of spatial information and interaction with 3D CAD models inside an immersive virtual environment (IVE). Such capabilities have shown the potential to mitigate the cognitive load needed for the visual perception of spatial information and, consequently, enhance design understanding and DR performance. Thus, an increasing number of studies have explored the effect of IVR technology on DR activities in different domains. However, determining when the implementation of IVR technology rather than a conventional user interface for DRs in mechanical engineering PD projects will be beneficial remains unclear. Hence, a conceptual DR experimental study was conducted to investigate the differences in the ability of engineering students to identify mechanisms and understand their functions when a design solution for a technical system is presented in an IVE by IVR technology and in a non-immersive virtual environment (nIVE) by a conventional user interface (monitor display, keyboard, and mouse). Data were collected by performing DR tasks and having participants complete a prior experience questionnaire, presence questionnaire, and mental rotations test. Findings of the study indicate that IVR does not support an enhanced ability of engineering students to identify mechanisms and understand their functions compared with a conventional user interface.     

A 13.56 MHz Rectifier Based on Fully Inkjet Printed Organic Diodes

The increasing diffusion of portable and wearable technologies results in a growing interest in electronic devices having features such as flexibility, lightness-in-weight, transparency, and wireless operation. Organic electronics is proposed as a potential candidate to fulfill such needs, in particular targeting pervasive radio-frequency (RF) applications. Still, limitations in terms of device performances at RF, particularly severe when large-area and scalable fabrication techniques are employed, have largely precluded the achievement of such an appealing scenario. In this work, the rectification of an electromagnetic wave at 13.56 MHz with a fully inkjet printed polymer diode is demonstrated. The rectifier, a key enabling component of future pervasive wireless systems, is fabricated through scalable large-area methods on plastic. To provide a proof-of-principle demonstration of its future applicability, its adoption in powering a printed integrated polymer circuit is presented. The possibility of harvesting electrical power from RF waves and delivering it to a cheap flexible substrate through a simple printed circuitry paves the way to a plethora of appealing distributed electronic applications.