Exchanger Network Research Articles

An efficient group synchronization of chaos-tuned neural networks for exchange of common secret key

An efficient group synchronization of chaos-tuned neural networks for exchange of common secret key

An efficient and random synthesis method for mass exchange networks with multi-component using a node-based vertical non-structural model

Mass exchange network (MEN) synthesis is an important technique to ensure efficient purification of industrial waste gas sources and water streams. However, most existing models for MEN synthesis are not capable of dealing with multi-component problems and achieving optimal designs. In this study, an innovative process integration strategy based on a node-based vertical non-structural model (NV-NSM) is proposed. The developed strategy allows for a more random representation of process configuration and aids in handling both single- and multi-component problems. The NV-NSM arranges several groups of main nodes in the process streams and the sub-nodes in their branches and results in design configurations by connecting any two sub-nodes on the rich and lean streams at the same main node number. When dealing with multi-component synthesis, the number of tray column is directly optimized to balance the mass transfer needs of different components. As part of the current investigation, the random walk algorithm with compulsive evolution (RWCE) is established to realize the simultaneous optimization of multiple variables, including the mass transfer loads, the number of trays, the stream split ratios, and the flowrates of lean streams. Furthermore, the fine-search strategy based on the RWCE is applied to improve global and local optimization performance. Finally, the proposed method is applied to four MEN cases featuring different exchanger specifications and considering both single and multiple components. The implementation and analysis result in more optimal solutions compared to those published in the literature, demonstrating the feasibility and effectiveness of the proposed method in analyzing and evaluating different MEN problems, including multi-component ones.

Heat cascade and heuristics to optimize ORC and identify the best internal configuration

Most ORC design optimization methods require specifying beforehand its internal configuration, and in particular its heat exchange network (HEN). This strongly limits the search space and thus, the resulting ORC performance. On the contrary, the heat cascade approach, a method to ensure physically sound heat transfers in thermal systems, can be adapted to optimize ORCs without having to specify the HEN configuration and instead, reveal the best configuration afterward. This work presents the gap between the traditional and heat cascade methods. Most importantly, it introduces heuristics to determine the best HEN configuration of an ORC designed with the heat cascade. The method is demonstrated for subcritical and transcritical reheat ORCs, for which 6 and 10 different HEN types were identified, respectively. Two case studies show how to use the method and calculate the stream split ratios present in the HEN types. Optimization results with the proposed method over a wide range of external conditions indicate an increase of the specific work output of up to 16% for the subcritical reheat cycle and 20% for the transcritical reheat cycle, when compared to the traditional optimization method.

The division of work in Senegalese conventional and alternative food networks: a contributive justice perspective

Labor conditions and rights are a key justice issue in agri-food systems, particularly in global, capitalized and industrialized food supply chains. While alternative food networks have emerged to produce and distribute food outside these logics, their ability to provide more equitable work conditions remains widely debated. We examine equity issues in the division of labor in food exchange networks in the horticultural sector of Senegal from the perspective of contributive justice. Contributive justice considers more broadly how different qualities of work are distributed and how work is perceived by the workers themselves. We performed 71 interviews of workers participating in three food exchange networks: (1) the conventional horticultural supply chain from the Niayes production area to Dakar, (2) an NGO-supported organic food network also supplying goods from Niayes to Dakar and (3) a community-supported agriculture scheme in a peri-urban coastal area. We investigated how functions and tasks are distributed along gender, ethnicity, place of origin and education characteristics of workers and how they qualify their tasks in terms of satisfaction and tediousness. We found a sharp labor division along gender, education and ethnic characteristics in the conventional network and a less sharp one in the two alternative networks. However, worker participants in alternative networks tend to belong to local elites and rarely include more disadvantaged people; they also tend to be less specialized and perform several functions, but do not necessarily express better work satisfaction. Workers who perform highly tedious tasks in the conventional network show rather surprising high work satisfaction. Based on these findings, we discuss the interplays between external and situated perceptions of work and the organization of food supply chains. This allows to critically examine the transformative potential of alternative food networks in the context of a lower-middle income country such as Senegal.

Process design and 4E analysis of different distillations of ethyl acetate/ethanol/cyclohexane separation based on extractive and pressure-swing properties

In this study, we proposed and compared extractive distillation, extractive pressure-swing distillation (EPSD), and pressure-swing distillation (PSD) techniques for the efficient separation of the ethyl acetate/ethanol/cyclohexane pressure-sensitive azeotropic mixture. Based on the influence of the extractant on the relative volatility and the analysis of the ternary phase diagram, dimethyl sulfoxide was selected as the extractant for extractive distillation. The pressure range for PSD was also determined. We employed the non-dominated sorting genetic algorithm II to optimize different processes, considering equipment and operation costs as the objective functions. After the multi-objective optimization, the decision solution was selected using the minimum distance method. A heat exchange network was also used to explore the energy-saving effects of different processes. The aforementioned processes were comprehensively evaluated based on economic, energy, environmental, and exergy analyses. The process results were correlated with the phase diagram based on the normal distance. The total annual cost, energy consumption, gas emissions, and energy loss of the improved processes decreased by more than 10%, 15%, 16%, and 3%, respectively, compared to those of the conventional process. Among the conventional and improved processes, EPSD and heat-integrated EPSD were identified as the best, respectively.

Interlinking research: the Big Exchange project

The Big Exchange project investigates large-scale exchange systems in Eurasia and Africa (8000–1 BC). We concentrate on raw materials of known origin (‘sourced finds’). Network analysis of tools and artificial intelligence methods are used to analyse the combined data sets. We invite broad collaboration on bimodal exchange networks.

Health information exchange network under collaboration, cooperation, and competition: A game-theoretic approach.

Health Information Exchange (HIE) network allows securely accessing and sharing healthcare-related information among healthcare providers (HCPs) and payers. HIE services are provided by a non-profit/profit organizations under several subscription plans options. A few studies have addressed the sustainability of the HIE network such that HIE providers, HCPs, and payers remain profitable in the long term. However, none of these studies addressed the coexistence of multiple HIE providers in the network. Such coexistence may have a huge impact on the behavior of healthcare systems in terms of adoption rate and HIE pricing strategies. In addition, in spite of all the effort to maintain cooperation between HIE providers, there is still a chance of competition among them in the market. Possible competition among service providers leads to many concerns about the HIE network sustainability and behavior. In this study, a game-theoretic approach to model the HIE market is proposed. Game-theory is used to simulate the behavior of the three different HIE network agents in the HIE market: HIE providers, HCPs, and payers. Pricing strategies and adoption decisions are optimized using a Linear Programming (LP) mathematical model. Results show that the relation between HIEs in the market is crucial to HCP/Payer adoption decision specially to small HCPs. A small change in the discount rate proposed by a competitive HIE provider will highly affect the decision of HCP/payers to join the HIE network. Finally, competition opened the opportunity for more HCPs to join the network due to reduced pricing. Furthermore, collaborative HIEs provided better performance compared to cooperative in terms of profit and HCP adoption rate by sharing their overall costs and revenues.

Multi-objective evolutionary optimization for multi-period heat exchanger network retrofit

Increase in energy efficiency and reduction in greenhouse gas (GHG) emissions in industry are important steps towards a more sustainable economy. Due to the growing share of high value-added industries multi-period operation becomes more common in process industry. Therefore, retrofit of existing multi-period production plants is a key aspect towards more sustainable production processes. Hence, in this work, an existing two-level evolutionary algorithm using a genetic algorithm and a differential evolution for multi-period heat exchanger network retrofit is extended to consider GHG emissions as a second objective to the total annual cost (TAC). The multi-objective problem is addressed by incorporating a non-dominated sorting genetic algorithm (NSGA-II) and hypervolume indicators into the algorithm. By analyzing an industrial case study of a potato chips production, the results of the multi-objective optimization shows that GHG emissions can be reduced by 50%. However, compared to the single-objective optimization, TAC is increased by 27%. By selecting capital costs and operating costs as objectives instead, similar results to the single-objective optimization are achieved showing that the results are highly dependent on the selection of the objectives. Further, changes in utility costs and caused emissions have a high impact on the results.

Inorganic Chemistry in Dalian University of Technology: Fundamental Science and Solution for Renewable Energy, Environment, Health, and Materials

Inorganic Chemistry in Dalian University of Technology: Fundamental Science and Solution for Renewable Energy, Environment, Health, and Materials

A Partial Prehistory of the Southwest Silk Road: Archaeometallurgical Networks along the Sub-Himalayan Corridor

Historical phenomena often have prehistoric precedents; with this paper we investigate the potential for archaeometallurgical analyses and networked data processing to elucidate the progenitors of the Southwest Silk Road in Mainland Southeast Asia and southern China. We present original microstructural, elemental and lead isotope data for 40 archaeological copper-base metal samples, mostly from the UNESCO-listed site of Halin, and lead isotope data for 24 geological copper-mineral samples, also from Myanmar. We combined these data with existing datasets (N = 98 total) and compared them to the 1000+ sample late prehistoric archaeometallurgical database available from Cambodia, Laos, Thailand, Vietnam and Yunnan. Lead isotope data, contextualized for alloy, find location and date, were interpreted manually for intra-site, inter-site and inter-regional consistency, which hint at significant multi-scalar connectivity from the late second millennium bc. To test this interpretation statistically, the archaeological lead isotope data were then processed using regionally adapted production-derived consistency parameters. Complex networks analysis using the Leiden community detection algorithm established groups of artefacts sharing lead isotopic consistency. Introducing the geographic component allowed for the identification of communities of sites with consistent assemblages. The four major communities were consistent with the manually interpreted exchange networks and suggest southern sections of the Southwest Silk Road were active in the late second millennium bc.

Whole-Exome sequencing analysis identified TMSB10/TRABD2A locus to be associated with carfilzomib-related cardiotoxicity among patients with multiple myeloma.

Proteasome inhibitor Carfilzomib (CFZ) is effective in treating patients with refractory or relapsed multiple myeloma (MM) but has been associated with cardiovascular adverse events (CVAE) such as hypertension, cardiomyopathy, and heart failure. This study aimed to investigate the contribution of germline genetic variants in protein-coding genes in CFZ-CVAE among MM patients using whole-exome sequencing (WES) analysis. Exome-wide single-variant association analysis, gene-based analysis, and rare variant analyses were performed on 603,920 variants in 247 patients with MM who have been treated with CFZ and enrolled in the Oncology Research Information Exchange Network (ORIEN) at the Moffitt Cancer Center. Separate analyses were performed in European Americans and African Americans followed by a trans-ethnic meta-analysis. The most significant variant in the exome-wide single variant analysis was a missense variant rs7148 in the thymosin beta-10/TraB Domain Containing 2A (TMSB10/TRABD2A) locus. The effect allele of rs7148 was associated with a higher risk of CVAE [odds ratio (OR) = 9.3 with a 95% confidence interval of 3.9-22.3, p = 5.42*10-7]. MM patients with rs7148 AG or AA genotype had a higher risk of CVAE (50%) than those with GG genotype (10%). rs7148 is an expression quantitative trait locus (eQTL) for TRABD2A and TMSB10. The gene-based analysis also showed TRABD2A as the most significant gene associated with CFZ-CVAE (p = 1.06*10-6). We identified a missense SNP rs7148 in the TMSB10/TRABD2A as associated with CFZ-CVAE in MM patients. More investigation is needed to understand the underlying mechanisms of these associations.

Matrix Non-Structural Model and Its Application in Heat Exchanger Network without Stream Split

Heat integration by a heat exchanger network (HEN) is an important topic in chemical process system synthesis. From the perspective of optimization, the simultaneous synthesis of HEN belongs to a mixed-integer and nonlinear programming problem. Both the stage-wise superstructure (SWS) model and the chessboard model are the most widely adopted and belong to structural models, in which a framework is assumed for stream matching, and the global optimal solution outside its feasible domain may be defined by the framework. A node-wise non-structural model (NW-NSM) is proposed to find more universal stream matching options, but it requires a mass of structural variables and extra multiple correction strategies. The aim of this paper is to develop a novel matrix non-structural model (M-NSM) for HEN without stream splits from the perspectives of global optimization methods and superstructure models. In the proposed M-NSM, the heat exchanger position order is quantized by matrix elements at each stream, and a HEN structure is initialized by the random generation of matrix elements. An approach for solving HEN problems based on a matrix real-coded genetic algorithm is employed in this model. The results show that M-NSM provides more flexibility to expand the search region for feasible solutions with higher efficiency than previous models.

Strategic generosity among local patrons: Place belonging and ethnic exclusion in a transforming lower‐income neighborhood of Tel Aviv

AbstractWorking at the intersection of exchange theory, urban anthropology, and ethnic and racial studies, this article offers an original perspective on the role of local patrons’ exchange networks in constructing place belonging during racial urban change. Inspired by a middle‐ground approach to reciprocity, embodying both solidarity and distrust within the same ethnic community, and manifested in an interracial context, the article proposes the integrative term of strategic generosity. The concept includes two interlinked layers: the combination of altruism and self‐interest in local patrons’ exchange practices within the same ethnic community, and patron exchange circles as mechanisms for the exclusion of racial Others reproducing boundaries between social groups. The case study is HaTikva—a lower‐income neighborhood in downtown Tel Aviv originally inhabited almost exclusively by disadvantaged Mizrahi Jews (of Middle Eastern origin), and more recently transformed by the arrival of African asylum seekers. Based on fieldwork conducted from 2010 to 2013 among long‐term Mizrahi residents, I argue that although local Mizrahi patrons use parental metaphors to describe their unconditioned giving to their own community; in fact, altruist and instrumental actions intermingle in the management of their reciprocity network. The exchange networks help vulnerable agents and enhance Mizrahi place attachment, but at the same time buttress the patrons’ own standing in the neighborhood and exclude the non‐Jewish African Others. These findings are discussed in the context of everyday life in a marginalized ethnic community as well as a barrier to integration and the concept's contribution to exchange theory more broadly. [strategic generosity, ethnic exclusion, exchange theory, place belonging, Mizrahi Jews, Tel Aviv]

A Diachronic Analysis of Obsidian Use at Chaco Canyon and the Influence of Social Factors on Obsidian Procurement

Chaco Canyon in New Mexico was the center of an extensive regional cultural system. The strength of Chaco's regional interactions has been partly defined by the presence of non–local goods including obsidian. We take a diachronic look at Chaco obsidian use from AD 500–1250 using the largest sample of XRF sourced obsidian available to date and combine this with technological analyses to identify significant changes in where and how Chacoans obtained and used obsidian. In the AD 700s obsidian from the more distant Jemez Mountains began to supplant the closer Mt. Taylor obsidian. The obsidian is of roughly equal quality, suggesting this shift relates to social factors and not raw material constraints. We find more variation over time in obsidian source use and acquisition strategies than previously noted. The patterning appears to relate to regional and local cultural diversity, social and organizational heterogeneity, and the development of new exchange networks.

Interdisciplinary analyses of the remains from three gallery graves at Kinnekulle: tracing Late Neolithic and Early Bronze Age societies in inland Southwestern Sweden

In this paper, we investigate the Scandinavian Late Neolithic and Early Bronze Age of Kinnekulle in southwestern Sweden. The above-mentioned periods in the study area are poorly understood and the archaeological record consists of a few stray finds and a concentration of 20 gallery graves. This study focuses on three of the gallery graves where commingled skeletons from successive burials were recovered. The human remains and the artefacts from the graves were used for discussing individual life stories as well as living societies with the aim of gaining new knowledge of the last part of the Neolithic and the beginning of the Early Bronze Age in southwestern Sweden. We focused on questions concerning health and trauma, mobility and exchange networks, and diet and subsistence of the people using the graves. Chronological, bioarchaeological, and biomolecular aspects of the burials were approached through the application of archaeological and osteological studies, as well as stable isotope, strontium isotope, radiocarbon, and mtDNA analyses. The study provides evidence for high mobility and diverse diets, as well as inhumations primarily dated to the transition between the Late Neolithic and Early Bronze Age. We suggest that the mountain plateau of Kinnekulle was mainly reserved for the dead, while the people lived in agriculture-based groups in the surrounding lower lying regions.

Crafting Fast and Efficient H2Evolution Electrocatalysts with Tactical Inclusion of Nucleobases

In order to achieve a hydrogen-driven energy infrastructure that is carbon-neutral, it is imperative that there be a synthetic catalyst that is developed from a non-noble metal. The unique interplay between the abundant transition metal containing an active site and the surrounding protein-based outer coordination sphere (OCS) is the essence of the remarkable H2 production displayed by hydrogenase enzymes. Here, we report a series of biomimetic cobalt complexes [Co(dimethylglyoxime)2(Nnucleobase derivative)Cl] crafted by strategic incorporation of a nucleobase and its derivatives (adenine, adenosine, adenosine monophosphate and hypoxanthine) around a common template. The nucleoside- and nucleotide-appended complexes electrocatalyze H2 evolution from neutral aqueous solutions at a rapid rate (turnover frequencies of ∼13 000 and ∼12 000 s–1, respectively) while operating at an overpotential of <400 mV. The intricate proton exchange network created between the different fractions of nucleobase derivatives is one of the prime reasons behind such fast and energy-efficient catalysis.

Challenges and opportunities for nutrient circularity: an innovation platform approach

AbstractTo reduce nutrient losses from the food system, it is necessary to improve biomass management and foster change. Such a change is often hindered by a lack of stakeholder interaction. Therefore, a qualitative case study and a practical application of the innovation platform approach in the Dutch-German border region Rhine-Waal were carried out to determine challenges and opportunities in the agro-food-waste system towards circular nutrient management in a nutrient-saturated and intensive animal production-dominated localized area. Twenty-one actors participated in a half-day workshop. A bottom-up approach was chosen as it increases trust between stakeholders and supports the acceptance of research processes. This study identified opportunities and challenges perceived by stakeholders participating in the innovation platform approach to facilitate a transition towards local circular nutrient management. We observed that challenges and opportunities exist at three levels: the individual actor’s level, the system level and the interconnection of the system with its wider environment. With a variety of stakeholders from animal and crop production to the food processing industry being present in the study area, the current demand and supply of biomass is very diverse. This diversity has been identified as a distinct opportunity for the establishment of a biomass exchange network in the area. However, information on demand and supply of nutrients between actors is currently scattered and information sharing hindered by the lack of direct monetary benefits. The lessons learned using the innovation platform approach are a first step towards improving nutrient circularity at a localized scale in nutrient-saturated areas.

Performance, Efficiency, and Flexibility Analysis of a High-Temperature Proton Exchange Membrane Fuel Cell-Based Micro-Combined Heat-and-Power System with Intensification of the Steam Methane Reforming Step by Using a Millistructured Reactor.

The complete simulation model of an existing 1 kW high-temperature proton exchange membrane (HT-PEM) fuel cell-based residential micro-combined heat-and-power process, including a compact intensified heat-exchanger-reactor, is developed in the simulation software ProSimPlus v3.6.16. Detailed simulation models of the heat-exchanger-reactor, a mathematical model of the HT-PEM fuel cell, and other components are presented. The results obtained by the simulation model and by the experimental micro-cogenerator are compared and discussed. To fully understand the behavior of the integrated system and assess its flexibility, a parametric study is performed considering fuel partialization and important operating parameters. The values of the air-to-fuel ratio = [30, 7.5] and steam-to-carbon ratio = 3.5 (corresponding to net electrical and thermal efficiencies of 21.5 and 71.4%) are chosen for the analysis of inlet/outlet component temperatures. Finally, the exchange network analysis of the full process proves that the process efficiencies can still be increased by further improving the process internal heat integration.

Networks of Specialized Knowledge

Recent research focused on the regions of Malatya and the northern Levant has allowed scholars to improve our understanding of the political history of the polities of Malizi and Palastina. The present article examines recent archaeological evidence from Arslantepe and several northern Levantine sites alongside a corpus of textual and iconographic data from the upper Euphrates and the northern Levant in an attempt to identify Early Iron Age networks of cultural exchange that resulted in shared specialized cultic and artistic knowledge. While networks of interaction between these regions may have begun as a product of persistent sociopolitical ties following the fragmentation of the Hittite Empire, this article proposes that it is due to the resilience of major cult centers that Malizi and Palastina were able to exchange specialized cultic knowledge and artistic traditions and employ them in the definition of their new Iron Age cultic and political communities.

Networks of trade and exchange along the Israeli Silk Road: the silk and cotton finds from Nahal Omer, Negev Desert

Excavations at Nahal Omer, an Early Islamic way station in the Negev Desert (sixth to ninth centuries AD), have yielded exotic textiles such as silks and cottons. Through a new study of these textiles, this project investigates the trade networks and global connectivity along this little-known artery of the Silk Road.