EXPERIMENTAL INVESTIGATION OF THE INFLUENCE OF MULTI-RECYCLING ON THE FRACTURE BEHAVIOR OF POST CONSUMER HIGH IMPACT POLYSTYRENE FROM DISPOSABLE CUPS EVALUATED BY THE J-INTEGRAL APPROACH.

The aim of the present paper is to study the effect of multi-recycling on the fracture behavior of high impact polystyrene from disposable cups. After collecting and washing the material, it was subjected to six cycles of recycling. After each cycle, it was subjected to tensile tests to determine the R-curves. The theory of the J-integral contour has been used for the development of a characterization method of the fracture strength appropriate to the case of this non-linear elastoplastic polymer material. To this end, the method of multiple specimens (Single edge notch tension SENT) of thin thickness was used, by introducing cracks of the same lengths to several identical test pieces. The results suggested a slight decrease in crack resistance of recycled high impact polystyrene, especially during the first cycle, demonstrated by a comparison of JIC values related to initiation of crack propagation. The fracture energy absorbed as a function of the cycles suggested a weakening within the material. ABSTRAK: Tujuan kajian ini adalah bagi mengkaji kesan tindak balas pada pelbagai peringkat-kitar semula ke atas kerapuhan polisterin berimpak tinggi pada cawan pakai buang. Selepas mengumpul dan membasuh cawan ini, terdapat enam peringkat kitar semula. Pada setiap peringkat, ianya akan melalui ujian tegangan bagi mendapatkan lengkung-R. Teori kamiran-J kontur telah digunakan bagi mencipta kaedah khas bagi mengkaji kekuatan retakan bersesuaian bagi kes bahan polimer elastoplastik yang tidak-linear. Sehingga kini, kaedah Regangan Tepi Takuk Tunggal (SENT) telah digunakan pada spesimen berketebalan rendah, dengan menghasilkan keretakan sama panjang di permulaan kajian di buat pada pelbagai bahan uji yang serupa. Dapatan kajian menunjukkan rintangan pada retakan telah berkurang sedikit pada polisterin kitar semula berimpak tinggi, terutama pada kitaran pertama, yang ditunjukkan pada nilai JIC pada permukaan rambatan retakan awal. Tenaga kerapuhan yang meresap pada setiap kitaran menunjukkan bahan telah melemah dari dalam.

Indoor Thermal Environment Challenges of Light Steel Framing in the Southern European Context

Over the past decades, Southern European residential architecture has been typically associated with heavyweight hollow brick masonry and reinforced concrete construction systems; however, more industrialised alternative systems have been gaining a significant market share, such as the light steel framing (LSF). Regardless of the proliferation of LSF buildings, a lack of experimental research studies have been performed on this construction system in terms of the indoor thermal environment and thermal comfort in the Southern European climate context. Moreover, a research gap also exists regarding experimental comparisons with typical brick masonry buildings. The present study focused on this research gap by characterising and comparing the performance of these two construction systems. A long-term experimental campaign was carried out, involving the construction and monitoring of two identical test cells, differing only by construction system. The test cells were located in Portugal and were monitored over an entire year. The results revealed that the LSF experimental test cell presented higher daily indoor air temperature fluctuations, leading to more extreme maximum and minimum values, closely following the outdoor dry bulb temperature variations. The more responsive behaviour was also reflected in the indoor thermal comfort analysis, with the LSF cell presenting slightly worse performance; however, some advantages were also observed regarding the LSF construction system, which could provide benefits during intermittent residential occupation, especially in mild climates, in which overheating is not a major concern.

Comparative analysis of Unity and Unreal Engine efficiency in creating virtual exhibitions of 3D scanned models

The main purpose of this work was to compare two game engines (Unreal Engine and Unity) in creating virtual exhibitions. The article is a scientific description of a test of their efficiency. For the needs of the research two identical test applications built on the basis of the same assets were created. Those applications enabled researchers to examine and compare the efficiency of engines in question, as well as familiarizing themselves with the workflow on each platform. The comparative analysis of gathered data let more effective solution to emerge, which happens to be Unity engine.

Hydrodynamic characteristics of vertical and quadrant face pile supported breakwater under oblique waves

This paper presents the results from a comprehensive experimental study on the Quadrant Face Pile Supported Breakwater (QPSB) in two different water depths exposed to three different oblique wave attacks. The results are compared with that for a Vertical face Pile Supported Breakwater (VPSB) for identical test conditions. The paper compares the reflection coefficient, transmission coefficient, energy loss coefficient, non-dimensional pressure, and non-dimensional run-up as a function of the relative water depth and scattering parameter. The results obtained for QPSB are validated with existing results. The salient observations show that QPSB experiences better hydrodynamic performance characteristics than the VPSB under oblique waves.

Alternative Blade Profile based on Savonius Concept for Effective Wind Energy Harvesting

The drag-based vertical-axis Savonius wind rotor is a potential candidate for harvesting renewable energy. It is very simple in design and can be deployed as an off-the-grid electricity system in remote locations having no access to electricity. The present work aims to develop a novel blade profile for the Savonius rotor in order to improve its performance. In that connection, an arc-elliptical-blade profile has been developed and rotor performance has been assessed through wind tunnel testing at three different Reynolds numbers (Re = 87039, 107348, and 131066). Further, its performance is compared to that of a conventional semicircular-bladed rotor under identical test conditions. The experiments revealed the maximum power coefficient (CPmax) of 0.11, 0.162, 0.213 at Re = 87039, 107348, and 131066, respectively for the arc-elliptical-bladed rotor. To complement the experimental findings and to examine the flow behaviour around the rotor blades, the computational fluid dynamics (CFD) simulations have also been performed using ANSYS FLUENT software. The local torque is found to be greater around the advancing arc-elliptical blade than around the advancing semicircular blade. It has been also noticed that the pressure distributions over concave sides are similar regardless of the blade shape.

Sequential SEM imaging of microbial calcite precipitation consolidation treatment

Cultural heritage built from limestone is prone to deterioration by chemical weathering, a natural process, that is enhanced by pollution. There are many historic monuments built from calcareous rocks that suffer from deterioration, and thus there have been a number of approaches over the last few decades to consolidate these types of rocks and surfaces. Using natural biological processes by fostering the activity of calcite-producing bacteria, also referred to as biomineralization, is one strategy that has also been commercialized. The base of proving the effectiveness of any surface treatment is the observation of the surface at sequential stages before and after treatment, as well as after exposure to weathering. Due to the heterogeneity of natural materials and processes, our aim was to observe identical test areas at the micron scale throughout the observation period. In order to achieve this on a tungsten SEM, we employed a beam deceleration accessory that allowed low kV imaging on non-conductive surfaces at a sufficiently high image resolution with a modified sample holder accommodating drill cores of 25 mm diameter and up to 15 mm height. The presented method is capable of producing time-sequenced images on the same test area on natural rock surface samples without manipulation for imaging purposes. This offers interesting perspectives for effective documentation of such processes in various fields.

Construction and Performance Testing of a Fast-Assembly COVID-19 (FALCON) Emergency Ventilator in a Model of Normal and Low-Pulmonary Compliance Conditions

IntroductionThe COVID-19 pandemic has revealed an immense, unmet and international need for available ventilators. Both clinical and engineering groups around the globe have responded through the development of “homemade” or do-it-yourself (DIY) ventilators. Several designs have been prototyped, tested, and shared over the internet. However, many open source DIY ventilators require extensive familiarity with microcontroller programming and electronics assembly, which many healthcare providers may lack. In light of this, we designed and bench tested a low-cost, pressure-controlled mechanical ventilator that is “plug and play” by design, where no end-user microcontroller programming is required. This Fast-AssembLy COVID-Nineteen (FALCON) emergency prototype ventilator can be rapidly assembled and could be readily modified and improved upon to potentially provide a ventilatory option when no other is present, especially in low- and middle-income countries.HypothesisWe anticipated that a minimal component prototype ventilator could be easily assembled that could reproduce pressure/flow waveforms and tidal volumes similar to a hospital grade ventilator (Engström CarestationTM).Materials and MethodsWe benched-tested our prototype ventilator using an artificial test lung under 36 test conditions with varying respiratory rates, peak inspiratory pressures (PIP), positive end expiratory pressures (PEEP), and artificial lung compliances. Pressure and flow waveforms were recorded, and tidal volumes calculated with prototype ventilator performance compared to a hospital-grade ventilator (Engström CarestationTM) under identical test conditions.ResultsPressure and flow waveforms produced by the prototype ventilator were highly similar to the CarestationTM. The ventilator generated consistent PIP/PEEP, with tidal volume ranges similar to the CarestationTM. The FALCON prototype was tested continuously for a 5-day period without failure or significant changes in delivered PIP/PEEP.ConclusionThe FALCON prototype ventilator is an inexpensive and easily-assembled “plug and play” emergency ventilator design. The FALCON ventilator is currently a non-certified prototype that, following further appropriate validation and testing, might eventually be used as a life-saving emergency device in extraordinary circumstances when more sophisticated forms of ventilation are unavailable.

Investigation of Ga Doping for Non-stoichiometric Sodium Bismuth Titanate Ceramics

The electrical performance of Ga3+ doping Na0.5Bi0.5TiO3-based oxygen ion conductor was studied. The Na0.52Bi0.47Ti1−xGaxO3−δ (x = 0, 0.01, 0.015, 0.02) samples were fabricated by the means of traditional solid-state reaction. The results of AC impedance measurement show that the bulk conductivity of Na0.52Bi0.47Ti1−xGaxO3−δ samples decrease monotonously with the increase of Ga3+ doping. At 673 K, the bulk conductivity of the Na0.52Bi0.47Ti0.98Ga0.02O3−δ sample is 7.19×10− 4 S/cm, which is lower than that of Na0.52Bi0.47TiO3−δ sample under the identical test temperature. The highest total conductivity emerges in the Na0.52Bi0.47Ti0.99Ga0.01O3−δ sample with 1.387×10− 4 S/cm at 623 K for the Ga3+ doping content of 1 mol%, which demonstrate that a slight of Ga3+ doping supports the enhancement of the total conductivity. A relaxation peak was observed in the Na0.52Bi0.47Ti1−xGaxO3−δ compounds. As the Ga3+ ions were introduced into the Na0.52Bi0.47TiO3−δ compound, there is an increasing trend of the relaxation activation energy educed by the internal friction test. In addition, the oxygen relaxtion height of Na0.52Bi0.47Ti1−xGaxO3−δ samples decreases along with the introduction of the Ga3+ doping, suggesting that the introduction of the Ga3+ leads to the decrease of mobile oxygen vacancy .

Effect of Calcium Carbonate Particle Size on the Scratch Resistance of Rapid Alkyd-Based Wood Coatings

Polymer-based wood coatings are used for aesthetic purposes as well as to protect wood surfaces, especially under external conditions. High-hardness mineral fillers are thought to enhance the resistance of these polymer coatings to wear and scratching. However, recent studies suggest that the relatively low-hardness mineral calcite (CaCO3, Mohs hardness of 3) performs similarly to harder minerals under external conditions. It can replace more expensive hard minerals, thus driving research interest in its use. In this study, CaCO3 powders with different grain sizes were applied to rapid alkyd-based coating formulations, and the effect of CaCO3 particle size on the scratch behavior of the coatings was investigated under identical test conditions. The scratch morphologies, scratch hardness, and roughness values of the scratched surfaces indicated that the surfaces of the rapid alkyd-based wood coatings including finer-grained CaCO3 experienced plastic plowing-type deformation in the form of regular, narrow, and shallow scratches, showing high scratch resistance. Coatings using coarser-grained CaCO3 experienced more extensive plastic deformation of the plowing–tearing type owing to the weaker filler–polymer interface and the breakage of larger coating pieces from the coating surface.

Lossless integration of multiple electronic health records for identifying pleiotropy using summary statistics

Increasingly, clinical phenotypes with matched genetic data from bio-bank linked electronic health records (EHRs) have been used for pleiotropy analyses. Thus far, pleiotropy analysis using individual-level EHR data has been limited to data from one site. However, it is desirable to integrate EHR data from multiple sites to improve the detection power and generalizability of the results. Due to privacy concerns, individual-level patients’ data are not easily shared across institutions. As a result, we introduce Sum-Share, a method designed to efficiently integrate EHR and genetic data from multiple sites to perform pleiotropy analysis. Sum-Share requires only summary-level data and one round of communication from each site, yet it produces identical test statistics compared with that of pooled individual-level data. Consequently, Sum-Share can achieve lossless integration of multiple datasets. Using real EHR data from eMERGE, Sum-Share is able to identify 1734 potential pleiotropic SNPs for five cardiovascular diseases.