Rapid Prototyping of Moulds for PDMS-based Microfluidic Chips

To shorten the production time for PDMS-moulds by additive manufacturing (AM) several 3D printers have been investigated in comparison to standard micro-milling by producing benchmark structures. These are evaluated regarding their shape accuracy, the transparency of the casted PDMS which is linked to the surface quality of the mould, and the production time until the moulds are ready to use. Even though the additively manufactured moulds showed significantly better surface quality and shorter production time, the necessary shape accuracy for non-square-structures or structures with < 250 μm edge length could not be achieved due to limiting factors like nozzle diameter, size of the digital micromirror device or spot size of the LCD-panel.

Modelling the nonlinear static response of a 2-storey URM benchmark case study: comparison among different modelling strategies using two- and three-dimensional elements

This paper aims at comparing the use of different software environments for the study of a simple unreinforced masonry building through nonlinear static analyses. The presented results are part of a wider research project conducted within the ReLUIS consortium, and specifically within a research task whose purpose is providing practitioners with results and tools for an aware employment of commercial software packages for modelling masonry structures. In this study one of the benchmark structures of the research program is analysed; a two-story building characterized by rigid horizontal diaphragms, considering different configurations in terms of openings arrangements and effectiveness of ring beams, is subjected to seismic load conditions. Software packages considering two- and three- dimensional structural models are employed, and the obtained results are compared in terms of capacity curves and collapse mechanisms. One of the critical aspects on the basic assumptions made by software in terms of way to apply the horizontal loads is further investigated. In addition, the role of the shear strength is analysed correlating the mechanical properties to be adopted with micro- and macro- models. The considered models present very different features, and the analogies and differences obtained in the results are critically interpreted in view of the different hypotheses made by the software tools in terms of modelling strategies and adopted constitutive laws.

SEISMIC ASSESSMENT OF CONTEMPORARY VERSUS OLD URBAN FRAME BUILDINGS

This comparative study probabilistically assesses the relative safety margins of code-compliant and pre-seismic code RC buildings with different heights in a region of medium seismicity. Detailed structural design and fiber-based modeling of six benchmark structures, namely two code-compliant buildings and two pre-code structures before and after retrofit, are undertaken to develop fragility functions using several earthquake records representing the most critical seismic scenario in the study area. Several inelastic dynamic analyses are performed to assess the seismic response and derive a range of fragility functions for the six benchmark buildings. Compared with contemporary structures, the study highlights the vulnerability of pre-code buildings due to the insufficient stiffness, strength, and ductility provided by their lateral force resisting systems. A practical retrofit solution for pre-code structures is subsequently assessed using the methodology adopted for other modern and old buildings. The probabilistic assessment results confirmed the comparable seismic performance of the retrofitted and code-conforming buildings. The comparative study, which provided insights into the differences between code-compliant versus pre-seismic code buildings before and after retrofit, contributes to reducing earthquake losses and improving community seismic resilience in earthquake-prone regions.

Benchmarking the software packages to model and assess the seismic response of unreinforced masonry existing buildings through nonlinear static analyses

Seismic modelling of unreinforced masonry (URM) buildings is addressed worldwide according to different approaches, not only at research level, but also in the current engineering practice. The analysts have so many different possible choices in interpreting the response of the examined structure and in transferring them into the model for the assessment that the achievable results may turn out in a huge scattering, as also testified by various comparative studies already available in the literature. Within this context, this paper is an overview of a wide research activity addressed to the benchmarking of software packages for the modelling and seismic assessment through nonlinear static analyses of URM buildings. The activity conveyed the effort of many experts from various Italian universities and was funded by the Italian Department of Civil Protection within the context of the ReLUIS projects. The main objective of the research is the critical analysis and the systematic comparison of the results obtained by using several modelling approaches and software package tools on selected benchmark examples in order to provide a useful and qualified reference to the engineering and scientific community. To this aim, different benchmark examples—of increasing complexity, ranging from the single panel to 3D existing buildings—have been specifically designed. While other papers from the teams involved in the research project delve on the specific results achieved on each of these case studies, this paper illustrates an overview on such benchmark structures, their purpose and the standardized criteria adopted to compare the results. Moreover, the whole set of benchmark case-studies is made available in this paper through their detailed input data allowing to be replicated also by other researchers and analysts.

The Influence of Additive Manufacturing Processes on the Performance of a Periodic Acoustic Metamaterial

Advancements in 3D print technology now allow the printing of structured acoustic absorbent materials at the appropriate microscopic scale and sample sizes. The repeatability of the fundamental cell unit of these metamaterials provides a pathway for the development of viable macro models to simulate built-up structures based on detailed models of the individual cell units; however, verification of such models on actual manufactured structures presents a challenge. In this paper, a design concept for an acoustic benchmark metamaterial consisting of an interlinked network of resonant chambers is considered. The form chosen is periodic with cubes incorporating spherical internal cavities connected through cylindrical openings on each face of the cube. This design is amenable to both numerical modelling and manufacture through additive techniques whilst yielding interesting acoustic behaviour. The paper reports on the design, manufacture, modelling, and experimental validation of these benchmark structures. The behaviour of the acoustic metamaterial manufactured through three different polymer-based printing technologies is investigated with reference to the numerical models and a metal powder-based print technology. At the scale of this microstructure, it can be seen that deviations in surface roughness and dimensional fidelity have a comparable impact on the experimentally measured values of the absorption coefficient.

An Analysis of Pay-for-Performance Schemes and Their Potential Impacts on Health Systems and Outcomes for Patients

Pay-for-performance (P4P) programs have been introduced into the Canadian medical system in the last decades. This paper examines the underlying characteristics of P4P and describes both their advantages and drawbacks. Most P4P programs provide the advantage of rewarding medical acts, thus providing an incentive to take on complex patients. There is a variety of nuanced P4P initiatives, which provide financial incentive according to differing criteria, based on quality measures, incentives, and/or benchmark structures. However, there is no conclusive evidence demonstrating that P4P programs provide better value for money than traditional pay schemes, regardless of particular structural choices. Some evidence has even shown that P4P may be detrimental, especially in disadvantaged and high-risk populations. Additionally, there are a number of ethical and practical concerns that arise with the use of P4P, such as the risk of financial incentives being misused or misinterpreted and patients being refused or referred during treatment. P4P initiatives require careful examination and the creation of solid, evidence-based criteria for evaluation and implementation in Canadian medical systems.