As supply chain resilience becomes a growing priority across industries, there emerges a need for decision support tools for advanced manufacturing planning under uncertainty. The pharmaceutical industry is a representative case, with manufacturers catering for emerging gene therapy and vaccine applications reporting delays and shortages in recent years due to the unforeseen pandemic, the need to rapidly re‐purpose manufacturing resources, combined with uncertain process performance of established capacity. Whilst process uncertainty is often quantifiable, tackling unforeseen demands requires the establishment of flexible production platforms. To this end, we present a framework for the quantification of network design flexibility integrating quantified process uncertainty. Network reliability metrics are quantified through scenario‐based chance constraint programming and solution quality is tested via Monte Carlo simulation. Cost‐reliability plots are obtained to pinpoint the required costs and capacity to meet a target probability of product demand satisfaction. Given an upper bound in cost and fixed design, the tool is also used to map out a feasible solutions space, quantifying maximum network reliability. Improving network reliability with this proactive approach supports supply chain resilience, as the impact of unexpected events can be understood and mitigated a priori.
This review presents the transformative potential of powder bed fusion (PBF) in manufacturing orthopedic implants, with a particular focus on β‐Ti‐Nb‐based ternary and quaternary titanium alloys. These alloys, such as Ti–18Zr–14Nb, Ti–29Nb–13Ta–4.6Zr, and Ti–35Nb–7Zr–5Ta (TNZT), offer significant advantages over conventional materials like Co–Cr alloys and Ti–6Al–4V due to their lower Young's modulus, excellent biocompatibility, and reduced stress shielding effects. The review covers the period from 2015 to September 2024 and highlights advancements in PBF‐fabricated β‐Ti alloys, emphasizing their potential to improve implant longevity and patient outcomes by minimizing the risks of implant failure associated with conventional materials.
This study explores how a sieving step of waste cellulosic fiber and fine (WCFF) mixture affects the performance of WCFF‐loaded polypropylene (PP) composites and whether the separation of fines from fibers offers an added benefit. The WCFF samples were downsized, and four different filler size ranges were sieved using a series of mesh sizes from 4 to 0.85 mm. The WCFF/PP composites were then compounded at 20 wt.% loading of WCFF using a twin‐screw extruder. Incorporating WCFF increased the tensile strength to 41.28 MPa and the modulus to 3207 MPa, accounting for 28% and 38% enhancements, respectively. Interestingly, the greatest improvements were associated with the nonsieved WCFF case, and the sieved WCFF fibers provided only marginal enhancements over virgin PP. The outperformance of nonsieved WCFF was attributed to the synergistic reinforcement of hybrid fibers and fines as well as the maintenance of longer fibers in the system. However, the strain at break and impact strength of PP decreased after introducing WCFF. Moreover, the complex viscosity and storage modulus increased with an increase in the filler size, due to the formation of a more effective percolative network. The PP's crystallinity exhibited a relatively strong dependency on the sieving, where WCFF samples with short‐aspect‐ratio fillers promoted the crystallinity significantly. It was also found that the WCFF degradation onset temperature increased once it was incorporated into PP. This study suggests that waste cellulosic feedstocks can be utilized as a reinforcement without additional sieving to manufacture high‐performance and cost‐effective composites.
The short lifespan of plastics, particularly in the packaging sector, results in rapid accumulation of plastic waste, with polypropylene being a major contributor. Chemical recycling is gaining increasing attention as a strategy in managing plastic waste, facilitating the transition from a linear to a circular economy. This study presents a comprehensive techno‐economic analysis (TEA) of a polypropylene recycling process via pyrolysis designed for a facility in the Southern United States, processing 300 kt of waste annually. The process was modeled using Aspen Plus for energy and mass balance and Aspen Process Economic Analyzer for capital cost estimations, with additional manual calculations for operating costs. Economic viability was assessed through net present value (NPV), internal rate of return (IRR), and Minimum Fuel Selling Price (MFSP). Results show that recycling polypropylene via catalytic pyrolysis is economically viable, with a NPV exceeding $330 million and an IRR of 29.6% over a 30‐year lifespan. The base case (300 kt/year) demonstrates the most promising financial viability, with high IRR and favorable ROI. Sensitivity analysis highlights the impact of market factors and operational costs on the economic viability of the process. Equipment cost breakdown shows that the “Storage” area, particularly the costs associated with hydrogen storage, is a significant contributor to the total capital investment. This finding highlights the importance of on‐site hydrogen production to further reduce capital investments and operational costs.
Gas stripping is an effective means to remove dissolved gases from liquids. To address the drawbacks of previous technologies, a unique planar bubbly cyclone (PBC) for continuous gas–liquid mass transfer is designed. This PBC meets the requirements of gas stripping, including a lower gas‐to‐liquid volumetric flow rate. A swirling flow and liquid backflow are formed under the constraints of the guide vanes and the cylinder wall. The population balance model accurately predicts the bubble diameter (1 to 6 mm), while the Kawase correlation gives excellent results and is in good agreement with the experimental data (±0.001 m/s). The accurate estimation, based on the assumption of gas plug flow and a well‐mixed liquid flow, gives volumetric mass transfer coefficients of 0.15–0.95 s −1 when the gas–liquid ratio was 0.01–1. Overall, the PBC provides an alternative approach to gas stripping, exhibiting a low gas–liquid ratio, long‐term capabilities, and good reliability.
