Compressed air systems: Factors affecting the adoption of measures for improved efficiency

© 2018 eceee and the authors, Stockholm. The sustainability and competitiveness of industrial activities may strongly rely on increased energy efficiency. In that, compressed air could be one of the most expensive forms of energy in industry because of its low efficiency. Nonetheless, compressed air is widely used, and is considered as relevant in many facilities, accounting for even more than ten per cent of industrial electricity consumption in the EU, in US and in China. Moreover, it should be noted that the life-cycle cost of a compressed air system is mostly covered by the operating costs, so that most of the measures to lower energy consumption pay for themselves almost immediately, producing relevant monetary savings. Nevertheless, several studies show that the adoption rate of such Energy Efficiency Measures (EEMs) is still low. For this reason, we have carefully reviewed scientific and industrial literature over EEMs for Compressed Air Systems (CAS), so to get useful insights into the main factors leading to their adoption. Our study lays a good foundation for a novel framework aimed at describing and characterising EEMs in CAS, revealing that, so far scientific and industrial literature has mostly presented energy and economic factors, thus giving little room to other factors that still could be quite relevant for an effective EEM adoption, such as compatibility of the measure within the production system (e.g., adaptability to different conditions, presence of different pressure loads), complexity of the production system (e.g., accessibility for operational activities, expertise required for implementation), observability of the performance (e.g., impact on air quality and/or safety). The framework could result in a valuable tool offering different perspectives in the decision-making of industrial managers and technology suppliers, as well as industrial policy-makers

Two is better than one? Order aggregation in a meal delivery scheduling problem

We address a single-machine scheduling problem motivated by a last-mile-delivery setting for a food company. Customers place orders, each characterized by a delivery point (customer location) and an ideal delivery time. An order is considered on time if it is delivered to the customer within a time window given by the ideal delivery time , where is the same for all orders. A single courier (machine) is in charge of delivery to all customers. Orders are either delivered individually, or two orders can be aggregated in a single courier trip. All trips start and end at the restaurant, so no routing decisions are needed. The problem is to schedule courier trips so that the number of late orders is minimum. We show that the problem with order aggregation is -hard and propose a combinatorial branch and bound algorithm for its solution. The algorithm performance is assessed through a computational study on instances derived by a real-life application and on randomly generated instances. The behavior of the combinatorial algorithm is compared with that of the best ILP formulation known for the problem. Through another set of computational experiments, we also show that an appropriate choice of design parameters allows to apply the algorithm to a dynamic context, with orders arriving over time

Evaluating the effects of stream power on rill flow resistance

Limited information is currently available on how sediment transport affects rill flow resistance and the influence of hydraulic variables, as stream power, on sediment transport capacity for rill flows. In this paper, the available measurements of hydraulic variables (flow depth, channel slope, mean flow velocity, Reynolds number, Froude number, and Darcy–Weisbach friction factor) carried out by Ban et al. (Measurement of rill and ephemeral gully flow velocities and their model expression affected by flow rate and slope gradient. Journal of Hydrology, 589, 125172) and Ban (Measurements and estimation of flow velocity in mobile bed rills. International Journal of Sediment Research, 38(1), 97–104) for fixed and mobile bed rills are used to test the applicability of a theoretically deduced rill flow resistance equation based on a power-velocity profile. The results allowed for stating that (i) the theoretical flow resistance approach can predict Darcy–Weisbach friction factor for flows over fixed and mobile beds, (ii) the stream power, dependent on flow discharge and slope, determines different flow behaviour, and (iii) the data are supportive of the slope independence hypothesis of rill velocity, for the mobile bed condition, only for the highest investigated discharge values (greater than 0.133 L s−1)

Mimicking Molecular Pathways in the Design of Smart Hydrogels for the Design of Vascularized Engineered Tissues

Biomaterials are pivotal in supporting and guiding vascularization for therapeutic applications. To design effective, bioactive biomaterials, understanding the cellular and molecular processes involved in angiogenesis and vasculogenesis is crucial. Biomaterial platforms can replicate the interactions between cells, the ECM, and the signaling molecules that trigger blood vessel formation. Hydrogels, with their soft and hydrated properties resembling natural tissues, are widely utilized; particularly synthetic hydrogels, known for their bio-inertness and precise control over cell-material interactions, are utilized. Naturally derived and synthetic hydrogel bases are tailored with specific mechanical properties, controlled for biodegradation, and enhanced for cell adhesion, appropriate biochemical signaling, and architectural features that facilitate the assembly and tubulogenesis of vascular cells. This comprehensive review showcases the latest advancements in hydrogel materials and innovative design modifications aimed at effectively guiding and supporting vascularization processes. Furthermore, by leveraging this knowledge, researchers can advance biomaterial design, which will enable precise support and guidance of vascularization processes and ultimately enhance tissue functionality and therapeutic outcomes

Pareto optimality in multilayer network growth

We model the formation of multi-layer transportation networks as a multi-objective optimization process, where service providers compete for passengers, and the creation of routes is determined by a multi-objective cost function encoding a trade-off between efficiency and competition. The resulting model reproduces well real-world systems as diverse as airplane, train and bus networks, thus suggesting that such systems are indeed compatible with the proposed local optimization mechanisms. In the specific case of airline transportation systems, we show that the networks of routes operated by each company are placed very close to the theoretical Pareto front in the efficiency-competition plane, and that most of the largest carriers of a continent belong to the corresponding Pareto front. Our results shed light on the fundamental role played by multi-objective optimization principles in shaping the structure of large-scale multilayer transportation systems, and provide novel insights to service providers on the strategies for the smart selection of novel routes

Metallothionein gene family in the sea urchin Paracentrotus lividus: Gene structure, differential expression and phylogenetic analysis

Metallothioneins (MT) are small and cysteine-rich proteins that bind metal ions such as zinc, copper, cadmium, and nickel. In order to shed some light on MT gene structure and evolution, we cloned seven Paracentrotus lividus MT genes, comparing them to Echinodermata and Chordata genes. Moreover, we performed a phylogenetic analysis of 32 MTs from different classes of echinoderms and 13 MTs from the most ancient chordates, highlighting the relationships between them. Since MTs have multiple roles in the cells, we performed RT-qPCR and in situ hybridization experiments to understand better MT functions in sea urchin embryos. Results showed that the expression of MTs is regulated throughout development in a cell type-specific manner and in response to various metals. The MT7 transcript is expressed in all tissues, especially in the stomach and in the intestine of the larva, but it is less metal-responsive. In contrast, MT8 is ectodermic and rises only at relatively high metal doses. MT5 and MT6 expression is highly stimulated by metals in the mesenchyme cells. Our results suggest that the P. lividus MT family originated after the speciation events by gene duplications, evolving developmental and environmental sub-functionalization

Optimum channel allocation in OFDMA multi-cell systems

This paper addresses the problem of allocating users to radio resources (i.e., sub-carriers) in the downlink of an OFDMA cellular system. We consider a classical multi-cellular environment with a realistic interference model and a margin adaptive approach, i.e., we aim at minimizing total transmission power while maintaining a certain given rate for each user. We discuss computational complexity issues of the resulting model and present a heuristic approach that finds optima under suitable conditions, or "reasonably good" solutions in the general case. Computational experiences show that, in a comparison with a commercial state-of-the-art optimization solver, our algorithm is quite effective in terms of both infeasibilities and transmitted powers and extremely efficient in terms of CPU times. © 2009 Springer Berlin Heidelberg

An intronic cis-regulatory element is crucial for the alpha tubulin Pl-Tuba1a gene activation in the ciliary band and animal pole neurogenic domains during sea urchin development

In sea urchin development, structures derived from neurogenic territory control the swimming and feeding responses of the pluteus as well as the process of metamorphosis. We have previously isolated an alpha tubulin family member of Paracentrotus lividus (Pl-Tuba1a, formerly known as Pl-Talpha2) that is specifically expressed in the ciliary band and animal pole neurogenic domains of the sea urchin embryo. In order to identify cis-regulatory elements controlling its spatio-temporal expression, we conducted gene transfer experiments, transgene deletions and site specific mutagenesis. Thus, a genomic region of about 2.6 Kb of Pl-Tuba1a, containing four Interspecifically Conserved Regions (ICRs), was identified as responsible for proper gene expression. An enhancer role was ascribed to ICR1 and ICR2, while ICR3 exerted a pivotal role in basal expression, restricting Tuba1a expression to the proper territories of the embryo. Additionally, the mutation of the forkhead box consensus sequence binding site in ICR3 prevented Pl-Tuba1a expression