Chain Configuration Research Articles

Technoeconomic Comparison of Scenarios for the Configuration of the Renewable Hydrogen Supply Chain in Colombia

Green hydrogen (RH2) can be used as a clean fuel and as energy vector. For this reason, it is a promising solution to the problems faced by the renewable energy (RE) industry. One determining factor for achieving its practical implementation is the correct configuration of its supply chain. This study compares different hydrogen supply chain (HSC) configurations. RH2 production will be by water electrolysis using RE in the Colombian Caribbean region, then, converted into Liquid Organic Hydrogen Carrier (LOHC), Cryogenic Liquid Hydrogen (LH2) or Compressed Hydrogen Gas (GH2), later, transported by trucks and delivered to meet the projected demand of the transportation sector. In the reference scenario, we found that the best alternative is to produce RH2 using an AEC-type electrolyser (alkaline electrolysis cells) powered by wind energy and convert it to GH2 at 350 bar for transportation and storage. Then, scenarios of demand, one-way distance and WACC were considered for projections between 2030 and 2050. The results showed that can be determined the one-way distance from which converting and transporting RH2 as LOHC is the best alternative and, also can be determined this limit for demand values, which allows us to identify the best configuration of the HSC.

A Dynamic Deployment Method of Security Services Based on Malicious Behavior Knowledge Base.

In view of various security requirements, there are various security services in the network. In particular, DDoS attacks have various types and detection methods. How to flexibly combine security services and make full use of the information provided by security services have become urgent problems to be solved. This paper combines the reasoning ability of the malicious behavior knowledge base to realize the dynamic deployment of the service function chain and dynamic configuration of the security service function. The method feeds back the information generated by the security service to the knowledge base. After the analysis of the knowledge base, the service function chain path and the security service configuration policies are generated, and these policies will be dynamically distributed to the security service function. Finally, security services can be dynamically arranged for different network traffic, realizing the coordinated use of various security services and improving the overall detection rate of the network. The experimental results show that by arranging the paths under the UDP and the TCP, the overall detection rate of the network can reach 99% and 88%, respectively, indicating that it has a good overall detection performance for multiple distributed denial of service (DDoS) attacks.

Solvent Quality Dependent Osmotic Pressure of Polymer Solutions in Two Dimensions.

Confined in two-dimensional planes, polymer chains comprising dense monolayer solutions are segregated from each other because of topological interaction. Although the segregation is inherent in two dimensions (2D), the solution may display different properties depending on the solvent quality. Among others, it is well-known in both theory and experiment that the osmotic pressure (Π) in the semidilute regime displays solvent quality dependent increases with the area fraction (ϕ) (or monomer concentration, ρ), that is, Π ∼ ϕ3 for good solvents and Π ∼ ϕ8 for Θ solvents. The osmotic pressure can be associated with the Flory exponent (or the correlation length exponent) for the chain size and the pair distribution function of monomers; however, they do not necessarily offer a detailed microscopic picture leading to the difference. To gain microscopic understanding into the different surface pressure isotherms of polymer solutions under the two distinct solvent conditions, we study the chain configurations of the polymer solution based on our numerical simulations that semiquantitatively reproduce the expected scaling behaviors. Notably, at the same value of ϕ, polymer chains in a Θ solvent occupy the surface in a more inhomogeneous manner than the chains in good solvent, yielding on average a greater and more heterogeneous interstitial void size, which is related to the fact that the polymer in the Θ solvent has a greater correlation length. The polymer configurations and interstitial voids visualized and quantitatively analyzed in this study offer microscopic understanding to the origin of the solvent quality dependent osmotic pressure of 2D polymer solutions.

Beam Steering and Signal Amplification Through Feedforward Networks. Part I: Transmission

Conventional and modern methods for beam steering in antennas and radar systems have one goal in common: to manipulate the phase shift between oscillating components, so that the direction of a radiating intensity pattern can be controlled. Typical components include arrays of nonlinear oscillators connected in a chain configuration. Modern methods for beam steering take advantage of the inherent nonlinearities of the individual components and of the collective dynamics of the array of oscillators to successfully manipulate phase shift. None of those methods include, however, signal amplification. In this manuscript, we introduce a novel array configuration: a feedforward network, which allows, simultaneously, for beam steering and signal amplification capabilities. We show that the amplitudes of certain bifurcating solutions in a feedforward network of nonlinear oscillators exhibit growth rates that are significantly larger than in other type of networks that operate near the onset of a Hopf bifurcation. Those branches of oscillations have the potential to lead to significant signal amplification of a radiating beam.

A stochastic reconstruction strategy based on a stratified library of structural descriptors and its application in the molecular reconstruction of naphtha

Molecular reconstruction is a rapid and reliable way to provide molecular detail of petroleum fractions, which is required in the kinetic modeling of petroleum conversation processes at the molecular level. In the typical stochastic reconstruction method, the estimation of properties of pseudo molecules that are generated by Monte Carlo sampling depends on the building of predefined molecular libraries, which is expensive and inaccessible for certain petroleum fractions. In this paper, a novel stochastic reconstruction strategy is proposed, which is based on a stratified library of structural descriptors. Properties of pseudo molecules generated in the novel strategy can be directly estimated by group contribution method in the condition of lacking predefined molecular libraries. In this strategy, the molecular building diagram comprises two steps. First, the ring structure is configured by determining the number of rings. Different from the length of chain adopted in the traditional stochastic reconstruction method, in the second step, number of structural descriptors (SDs) for binding site and chain were determined sequentially for the configuration of binding site and saturated acyclic hydrocarbon chain. These structural descriptors for binding site and chain were selected from group contribution methods. To count the number of partial overlapping sections between structural descriptors for chain, two supplementary structural descriptors were created. All possible saturated structures of hydrocarbon chains can be represented by structural descriptors at the scale of property estimation. This strategy separates the building of a predefined molecule library from the stochastic reconstruction process. The exact structures of pseudo molecules represented by structural descriptors in this work can be determined with sufficient chemical knowledge. Fifty naphtha samples are tested independently to demonstrate the performance of the proposed strategy and the results show that the estimated properties were close enough to the experimental values. This strategy will benefit the molecular management of petrochemical industries and therefore improve economic and environmental efficiencies.

Additive manufacturing: A framework for supply chain configuration

Using Resource Dependence Theory (RDT), this paper explores the changing state of Supply Chain (SC) complexities and dependencies resulting from Additive Manufacturing (AM) adoption, analysing implications for competitiveness. We utilised an adapted SC configuration framework to develop embedded case studies across the Aerospace, Automotive and Power Generation industries. The sample included fifteen companies deploying metal AM across three SC tiers. Using an abductive logic, our findings reveal that the complexity and dependency-reduction potential of AM depends on economic, industry, geographical, organisational and technological factors. We developed a conceptual framework for AM SC configuration and four propositions, which provide further insights into the interplay between SC complexities, dependencies and competitiveness. By utilising RDT, we contribute to the AM SC configuration literature by highlighting the mediating role that dependencies play in achieving competitiveness, as well as strategies adopted by firms to mitigate uncertainty. We also highlight the interplay between ‘relationship and governance’ and three other SC configuration dimensions in relation to competitiveness. Insights into the changing state of complexities and dependencies identified in this study could also support managerial decisions in AM SC design.

Key gene networks that control magnetosome biomineralization in magnetotactic bacteria.

Magnetotactic bacteria (MTB) are a group of phylogenetically and morphologically diverse prokaryotes that have the capability of sensing Earth's magnetic field via nanocrystals of magnetic iron minerals. These crystals are enclosed within intracellular membranes or organelles known as magnetosomes and enable a sensing function known as magnetotaxis. Although MTB were discovered over half a century ago, the study of the magnetosome biogenesis and organization remains limited to a few cultured MTB strains. Here, we present an integrative genomic and phenomic analysis to investigate the genetic basis of magnetosome biomineralization in both cultured and uncultured strains from phylogenetically diverse MTB groups. The magnetosome gene contents/networks of strains are correlated with magnetic particle morphology and chain configuration. We propose a general model for gene networks that control/regulate magnetosome biogenesis and chain assembly in MTB systems.

Digital ecosystems in global value networks: a multicriteria decision analysis approach

This paper shows a progress result of the ongoing research on the application of the multi-criteria decision-making Methodology (MCDM) and the Analytical Hierarchy Process (AHP) that allows for defining the most appropriate model in the measurement of the degree of maturity of global value chains, based on the methodological phases for decision making, through the analysis of existing measurement systems recognized worldwide, that allow selecting the alternatives and their attributes for comparison. In this phase of the research, the incidence of industry 4.0 in the processes of integration of supply chains for the conformation of digital ecosystems is highlighted, its incidence in the adaptive configurations of value chains, and the contribution of technology in the maturity of the same.

Technoeconomic Feasibility of a Sunflower Husk Fast Pyrolysis Value Chain for the Production of Advanced Biofuels.

Biofuels are required to reach the target set out by the European Commission's Transport mandate in the RED II (Renewable Energy Directive) for 2020-2030. To avoid indirect land use change, waste biomass resources such as sunflower husks can be used for advanced biofuel production. A process simulation and technoeconomic assessment of three fast pyrolysis plant scenarios were conducted. The nature of the waste feedstock has an effect on the value chain configuration, fast pyrolysis, and upgrading process design. Considering the difficulties with the transport and storage of biogenic waste due to low bulk density or hazardous and pathogenic content in case of transporting untreated sunflower husks, it is recommended to use a hub-and-spoke type of decentralized value chain configuration. The fast pyrolysis plants are located close to the feedstock, and the fast pyrolysis bio-oil (FPBO) is transported to a single upgrading facility, colocated at an existing refinery. The upgraded FPBO is then cofed into an FCC (fluidized catalyst cracker), where partially green biofuels such as gasoline and diesel are produced. For the fast pyrolysis process design, Scenario 2, treating 10 t/h of dry biomass with electricity and steam as coproducts, has the most favorable economic results with a total capital investment (TCI) of 78 million Euro and operating expenses (OPEX) of 6 million Euro.

Mechanism of action of cefiderocol.

Gram-negative bacilli are intrinsically resistant to many antibiotics due to the low permeability of their outer membrane. The most effective strategy to solve this problem has been the design of antibiotics that cross the membrane using specific transport systems. This is the case of cefiderocol, which, unlike cefepime or ceftazidime, has a chlorocatechol group at the end of the C-3 side chain. This group is recognized by transporters located in the outer membrane that allow cefiderocol to accumulate in the periplasmic space. Furthermore, cefiderocol is not a substrate for efflux pumps and the configuration of the side chains at C-7 and in particular at C-3 confer it a high stability against hydrolysis by most beta-lactamases of clinical interest including class A (KPC, BLEEs), C (ampC) or D (OXA-48) serine beta-lactamases and metallo-betalactamases (NDM, VIM. IMP). In order to better understand the mechanism of action of cefiderocol, the importance of iron in bacterial metabolism and the competition for iron between bacteria and host are reviewed.The indiscriminate and massive antibiotic use in the clinical practice and in agriculture or cattle during the past few decades has produced a serious world health problem that entails high morbidity and mortality: the antibiotic multi-drug resistance. In 2017 and 2019, the World Health Organization published a list of urgent threats and priorities in the context of drug resistance, which only included Gram-negative bacteria and specially focused on carbapenem-resistant Acinetobacter baumannii and Pseudomonas aeruginosa, as well as carbapenem and third generation cephalosporin-resistant Enterobacteriaceae. This scenario emphasizes the need of developing and testing new antibiotics from different families, such as new beta-lactams, highlighting cefiderocol and its original mechanism of action; new beta-lactamase inhibitors, with vaborbactam or relebactam among others; new quinolones such as delafloxacin, and also omadacycline or eravacycline, as members of the tetracycline family. The present work reviews the importance and impact of Gram-negative bacterial infections and their resistance mechanisms, and analyzes the current therapeutic paradigm as well as the role of new antibiotics with a promising future in the era of multi and pan-drug resistance.

A cluster analysis of the global wind power industry: Insights for renewable energy business stakeholders and environmental policy decision makers

AbstractIn light of an ongoing climate change and an increasing fragility of fossil energy supply due to global political tensions, the adoption of renewable energy sources is of utmost importance for economic and social prosperity. This study targets to endeavor major value chain configurations within the global wind power industry network based on a data set of 326 relationships established by the 10 globally leading wind turbine firms covering a time span of 15 years. We discuss the demand side and provide an overview of the main wind power investment target countries and compare the importance of different regions. On the supply side, we analyze and identify eight important firm clusters within the global wind power business network. Concerning our sample, we elaborate horizontal and vertical relationship links, their collaboration patterns, regional partner preferences, and their value chain competences, thus providing valuable insights into the competitive structures of the wind power industry. By doing so, we open the debate on appropriate and efficient firm strategies within renewable industries. As consequence, we provide robust empirical evidence on global wind power industry architectures and corresponding competitive firm forces for the future. As we found that the industry is currently divided into eight main global industry clusters, our study delivers valuable industry network insights addressing managerial, political, and socioeconomic decision makers in order to secure future ecological and economic prosperity in a challenging world.

McaA and McaB control the dynamic positioning of a bacterial magnetic organelle.

Magnetotactic bacteria are a diverse group of microorganisms that use intracellular chains of ferrimagnetic nanocrystals, produced within magnetosome organelles, to align and navigate along the geomagnetic field. Several conserved genes for magnetosome formation have been described, but the mechanisms leading to distinct species-specific magnetosome chain configurations remain unclear. Here, we show that the fragmented nature of magnetosome chains in Magnetospirillum magneticum AMB-1 is controlled by genes mcaA and mcaB. McaA recognizes the positive curvature of the inner cell membrane, while McaB localizes to magnetosomes. Along with the MamK actin-like cytoskeleton, McaA and McaB create space for addition of new magnetosomes in between pre-existing magnetosomes. Phylogenetic analyses suggest that McaA and McaB homologs are widespread among magnetotactic bacteria and may represent an ancient strategy for magnetosome positioning.

Mitigating Environmental Impact of Perishable Food Supply Chain by a Novel Configuration: Simulating Banana Supply Chain in Sri Lanka

As the world is moving into a sustainable era, achieving zero hunger has become one of the top three Sustainable Development Goals, applying a considerable amount of pressure on the agri-food systems to make decisions contemplating the sustainability dimensions. Accordingly, making effective supply chain decisions holistically while achieving sustainability goals has become a major challenge faced by the present agri-food systems. Thus, to address the challenge, a novel supply chain configuration addressing multiple supply chain decisions to reduce global warming potential (GWP) and post-harvest losses have been presented by taking the banana supply chain in Sri Lanka as a case study. In the proposed approach, farmers have been clustered based on their geo positions using K-Means clustering followed by route planning within clusters using a heuristics approach. Retailer points are catered by assigning to wholesalers optimally modeling as an assignment model and then route planning executed using a heuristic approach. The solution generated from the above approaches has been implemented on a simulation platform to calculate the overall supply chain performance including the transportation component, in terms of the net GWP, post-harvest losses, and lead time including routing operations. Simulated supply chain performance has been compared with the existing system and verified the performance of the proposed supply chain configuration. The suggested configuration has reduced the net GWP by 15.3%, post-harvest loss by 2.1%, lead time by 28.2%, and travel distance by 20.47%. The proposed configuration can be further improved by adding dynamic characteristics to the model.

Regional inequality in China during its rise as a giant exporter: A value chain analysis

AbstractChina's exports success has implications for regional income inequality, because most of its export products are manufactured in the coastal zone. We propose a value chain‐based accounting framework to quantify the contributions of exports to regional income inequality. We employ newly developed interregional input–output tables for China, which distinguish between processing export activities and ordinary export activities. We analyze the period 2002–2012, the decade during which China became the “Factory of the World.” We find that an RMB of processing exports contributed much more to regional inequality than an RMB of ordinary exports or domestic final demand. Still, changes in regional inequality (increasing in 2002–2007 and decreasing between 2007 and 2012) are much more due to rising ordinary exports in the first subperiod and the growth of domestic final demand coupled with changes in the configuration of value chains in the second.

Virtual Carbon Flow in China’s Capital Economic Circle: A Multi-Regional Input–Output Approach

The Capital Economic Circle (CEC) is the area with the largest economic aggregate in northern China and has a strong status in driving the economic development of China. However, the industrial structure dominated by high energy consuming industries leads to a large number of carbon dioxide emissions, and the imbalance between economic development and carbon emissions in CEC is serious; therefore, it is necessary to explore how to solve the carbon imbalance problem of the CEC by relying on interregional cooperation. Based on China’s multi-regional input–output tables of 2012, 2015 and 2017, this paper proposes the CEC carbon-extended, multi-regional input–output model to measure virtual carbon flow and analyze how the industrial structure leads to the imbalance of carbon flow distribution in CEC. Indicators such as direct carbon emission coefficients, complete carbon emission coefficients and carbon emissions pull coefficients of the industrial sectors in CEC are calculated and the physical carbon emission and virtual carbon flows among the industrial sectors and the regions are evaluated. The results show that there are potential constraints from the uncoordinated configuration of industrial innovation chains among the CEC, and the “carbon imbalance” of CEC is mainly reflected in the backward production technology of Hebei and its inefficient connection with the industrial innovation chain of Beijing and Tianjin. It is suggested that policymakers should promote the low-carbon production system and strengthen green energy development and utilization to enhance green development in CEC. In future research, we should pay attention to the updating method of the input–output table and the development of carbon circular networks. This study has implications for some areas of China and developing countries in Asia, which also have an imbalance between industrial economy development and carbon emissions, and a similarity in space structure and industry layout with CEC.

Thermal lensing in copper vapor laser oscillator-amplifier configuration: Its measurement, role and compensation

A novel technique to measure the resultant focal length of the thermal lens in an amplifier using collimated beam of the oscillator for copper vapour laser system demonstrated. The resultant focal length was estimated using ray tracing approach in a 40 W system (CVL-40). Effect of input electrical power and neon buffer gas pressure on the resultant focal length was studied. Role of equivalent thermal lens in master oscillator power amplifier (MOPA) configuration was evaluated. Compensation techniques for minimization of the thermal lensing effect for a MOPA chain were theoretically studied using ray tracing in an equivalent lensing model. Compensation of thermal lensing for an eight module MOPA chain with CVL-40 (38 mm bore, 1.8 m long, 40 W, 9 kHz) systems studied. An eight-module MOPA chain configuration with minimized thermal lensing based on optimized compensation techniques is proposed. Our study finds benefits for high power laser systems used in various industrial, research and development applications like micromachining, high speed photography, bio-medical applications and pumping dye lasers for spectroscopy.

Sustainability Impact Assessment of Forest Bioenergy Value Chains in Quebec (Canada)—A ToSIA Approach

Forest bioenergy value chains can offer attractive opportunities to promote economic development and mitigate climate change. However, implementing profitable and efficient forest biomass value chains requires overcoming barriers that continue to hinder the development of bioenergy systems in several jurisdictions. The objective of this study was to compare the economic, social, and environmental sustainability of various potential configurations of forest bioenergy value chains, including forest biomass supply and bioenergy production chains, in the Capitale-Nationale region of Quebec (Canada), which is a jurisdiction that has considerable forest resources but makes little use of bioenergy. We based our study on the ToSIA model parameterization and compared various policy measures, biomass supply, and logistics scenarios for 2008 and 2030. Our results showed that wood chip and pellet value chains in the Capitale-Nationale region would positively contribute to the regional economy in 2030, even in the absence of subsidies. Moreover, actions to increase biomass feedstock mobilization in 2030 would lead to an increase in gross value added, employment, and energy production in the region compared with 2008 and a greater increase than other considered policy or logistical measures. However, increased biomass feedstock mobilization would also mean higher relative GHG emissions and more fossil fuel energy input per unit of bioenergy than in the other scenarios. Conversely, optimizing biomass feedstock and combustion technologies could help minimize the fossil fuel energy input needed and GHG and some non-GHG pollutant emissions. Overall, our study suggested that implementing policy and logistical measures for forest biomass value chains could make the significant mobilization of forest bioenergy attainable and, in turn, Quebec’s 2030 bioenergy target of 17 petajoules realistic.

Modifying Frank–Kasper Mesophases by Modulating Chain Configuration in PDMS-b-PTFEA Copolymers

The common spherical mesophases observed from chemically distinct compounds have promoted extensive studies of packing structures in soft-matter self-assemblies. Here, we present a new approach for controlling sphere-packing phases by modulating homologous copolymer chain configurations. To this end, three sets of sample pairs, compositionally asymmetric polydimethylsiloxane-b-poly(2,2,2-trifluoroethyl acrylate) (PDMS-b-PTFEA) diblock copolymers (diBCPs) and their homologues containing the corresponding triblock copolymer (triBCP), are synthesized via atom transfer radical polymerization and designed with the consistent volume fractions of the core-forming PTFEA block, fPTFEA = 0.20, 0.18, and 0.15. We identify the formation of C15 and hexagonally close-packed (HCP) phases in the triBCP-containing PDMS-b-PTFEAs, whereas the σ and C14 phases are formed in their diBCP analogues, respectively. These phase shifts into C15 and HCP, due to molecular configuration differences, reveal a significant yet unrealized role of chain configurations and the associated chain size effects in determining the stable sphere-packing phases in BCP systems.

System dynamics approach for food inventory policy assessment in a humanitarian supply chain

In a humanitarian context, disaster relief operations handle in-kind donations and supplies required to assist the affected population. Among the most challenging operations in disaster relief is food aid supply, particularly in long-lasting humanitarian assistance. Food aid supply requires the design of inventory optimization methods adapted to disaster relief contexts to tackle over-stock, significant wastage levels, shortage, and protocols to distribute non-perishable items, such as canned tuna and rice, among others. This is due to the uncertain and changing conditions of disaster relief operations. In addition, most humanitarian food supply chains are unable to handle perishable products because of the lack of resources needed to perform the required logistic operations, respecting product shelf-life constraints. This study evaluated the capability of different humanitarian food supply chain configurations to distribute perishable products, such as vegetables and fresh meat, which can be obtained in agronomic-based economies, and can aid in providing the means for food distribution as well as the likelihood of fulfilling social and cultural aid based on the characteristics of the population. Consequently, a dynamic system model was proposed for comparing centralized and decentralized supply chain configurations. Further, the experimental results, considering a natural disaster in Colombia, facilitated the evaluation of the sensitivity of the system's key performance indicators in humanitarian logistics in terms of agility, recovery time, and efficiency in specific echelons. Furthermore, this study provides managerial insights to help humanitarian agencies design inventory management strategies for food assistance programs during relief operations in the aftermath of a disaster.

Material Properties, Dissolution and Time Evolution of PEGylated Lipid-Shelled Microbubbles: Effects of the Polyethylene Glycol Hydrophilic Chain Configurations.

Polyethylene glycol (PEG) is often added to the lipid coating of a contrast microbubble to prevent coalescence and improve circulation. At high surface density, PEG chains are known to undergo a transition from a mushroom configuration to an extended brush configuration. We investigated the effects of PEG chain configuration on attenuation and dissolution of microbubbles by varying the molar ratio of the PEGylated lipid in the shell with three (0%, 2% and 5%) in the mushroom configuration and two (10% and 20%) in the brush configuration. We measured attenuation through the bubble suspensions and used it to obtain the characteristic rheological properties of their shells according to two interfacial rheological models. The interfacial elasticity was found to be significantly lower in the brush regime (∼0.6 N/m) than in the mushroom regime (∼1.3 N/m), but similar in value within each regime. The dissolution behavior of microbubbles under acoustic excitation inside an air-saturated medium was studied by measuring the time-dependent attenuation. Total attenuation recorded a transient increase because of growth resulting from air influx and an eventual decrease caused by dissolution. Microbubble shell composition with varying PEG concentrations had significant effects on dissolution dynamics.