Exchanger Network Research Articles

Inverse system based decoupling design and control strategy for crude oil heat exchanger networks

This work focuses on a decoupling control approach for the crude oil heat exchanger network to improve the energy efficiency and achieve continuous energy saving. The desired control variables are identified by the signed directed graph (SDG) model based on the complex network theory. Then the principal component analysis (PCA) method and the evaluation index are employed to construct the initial controller as well as the control variables pairing. The presented system is a multi-input multi-output (MIMO) control system where the coupling problems are considered, and a decoupling control strategy based on the inverse system theory of neural network is proposed. The existence of the inverse system is proved by the reversibility derivation, and the original system is decoupled into two second-order subsystems. Consequently, the proposed decoupling control system is tested on the example of heat exchanger network (HEN) belonging to Crude Distillation Unit. The fluctuating value of temperature is reduced averagely by 57.1% compared with the non-decoupling control strategy and the mean absolute percentage error is within 0.02 under different operating conditions. The results show that the proposed decoupling control method has excellent decoupling performance and can improve the control performance of the system.

Thermal management of sodium-oxygen-hydrogen (Na-O-H) thermochemical water splitting for sustainable hydrogen production

Owing to environmental problems caused by the consumption of fossil fuels and the growing global demand for energy, interests in usage of hydrogen as a green energy carrier has grown. In particular, water is considered a prospect source for green hydrogen production. In this paper, a three-step sodium-oxygen-hydrogen (Na–O–H) thermochemical cycle, which is a newly developed cycle that can operate between 400 and 500 °C is implemented. Also, low number of steps, which results in less system complexity and easier system design is another advantage of the Na–O–H thermochemical cycle. In the first step of this study, a basic model of the three-step pure Na–O–H cycle is modeled in order to produce 1 kg/s of hydrogen. Moreover, output data from basic modeling is used for cycle energy management. Then, heat recovery is performed within the cycle streams to reduce the external energy demand and make the Na–O–H cycle more feasible. To achieve this objective, pinch method, which is an effective method for designing and optimizing plants is used. Several heat exchanger network designs have been developed and compared from different aspects. Finally, a design with the least heat requirement among others is selected and optimized based on total annualized cost objective function to introduce the optimum final design exchanger network. As a result of this work, it is found that using the final optimized design, external heating loads accounted for just 5.8% of the total load, while external cooling loads accounted for 19.3% of the total load. This implies that the Na–O–H thermochemical cycle recovered 74.7% of the energy required for heating and cooling of the streams. The implementation of the proposed heat exchanger network design boosts the overall energy efficiency of the Na–O–H thermochemical cycle. Using final heat recover scheme the overall efficiency of the cycle increased from 45.36% to 52.86%, representing an impressive 7.50% improvement. This significant achievement underscores the pivotal role of this study in developing an effective and optimized model for the Na–O–H thermochemical cycle, which holds great promise for future applications.

Information flow in the FTX bankruptcy: A network approach

This paper investigates the cryptocurrency network of the FTX exchange during the collapse of its native token, FTT, to understand how network structures adapt to significant financial disruptions, by exploiting vertex centrality measures. Using proprietary data on the transactional relationships between various cryptocurrencies, we construct the filtered correlation matrix to identify the most significant relations in the FTX and Binance markets. By using suitable centrality measures - closeness and information centrality - we assess network stability during FTX’s bankruptcy. The findings document the appropriateness of such vertex centralities in understanding the resilience and vulnerabilities of financial networks. By tracking the changes in centrality values before and during the FTX crisis, this study provides useful insights into the structural dynamics of the cryptocurrency market. Results reveal how different cryptocurrencies experienced shifts in their network roles due to the crisis. Moreover, our findings highlight the interconnectedness of cryptocurrency markets and how the failure of a single entity can lead to widespread repercussions that destabilize other nodes of the network.

Ferdinand Khittl's Die Parallelstraße : Ecological Thinking and the Implicated Subject

abstract: Ferdinand Khittl's Die Parallelstraße ( The Parallel Street , 1962) is an understudied docufiction from an early moment in the Young German Cinema. It hybridizes industrial film techniques, cross-sectional montage in particular, with experimental prose poetry to achieve an ecological mode of storytelling. These aesthetic strategies make a network of global extraction and exchange sensuously cognizable, facilitating the viewer's self-recognition as an implicated subject. In an early instance of multidirectional memory (Rothberg), representations of particular nodes in this network are shown to take up the project of Vergangenheitsbewältigung and unite it with postcolonial concerns around environmental degradation and exploitation throughout the Global South.

Development and empirical verification of non-uniformly layout semiconductor liquid cooling garment model based on CFD simulation

Personal cooling garments (PCGs) are important to help human body regulate its own thermal comfort under high temperature environments. This study focuses on the thermal comfort of personal cooling garment in high temperature environments, which is of great significance in the context of current climate warming and frequent extreme high temperature events. Traditional research on cooling garment mainly focuses on improving its cooling performance, but ignores how to improve human thermal comfort by optimizing cooling equipment and garment parameters. This study developed a semiconductor liquid cooling garment (SLCG) that can adjust and help the human body achieve optimal thermal comfort under different environmental conditions. Through computational fluid dynamics (CFD) simulation, this study established a human body model wearing SLCG to analyze the effects of parameters such as external ambient temperature, flow rate, and inlet water temperature on thermal comfort. Different from traditional research, this study proposed a heat exchange network design with non-uniformity layout, this layout accounted for the variations in heat dissipation across different regions of the human body, enabling targeted optimization of the cooling effect. The results show that among the five different pipe spacings, the spacing of 2–3.5 cm can most effectively improve human thermal comfort. Specifically, in an environment of 34 °C, the parameter combination of inlet water temperature of 24 °C and flow rate of 26 kg/h was selected; at 36 °C, the inlet water temperature was 22 °C and the flow rate was 40 kg/h; at 38 °C, the inlet water temperature was 20 °C and the flow rate was 54 kg/h. The accuracy of the newly developed numerical model was evaluated through a series of experiments. Validation efforts involved comparing the model’s numerical results with experimental outcomes derived from human trials. The error between the simulated and experimental temperatures at each inlet and outlet was confined to within 0.2 °C. The error of cooling power is within 8 %, which proves the accuracy of the numerical model and the rationality of SLCG optimal parameters. This study not only proposed a new SLCG design idea, filling the research gap on thermal comfort optimization in the field of cooling garment, but also provided a theoretical basis and practical reference for the future design of cooling garment in different high temperature environments.

Comprehensive techno-economic and environmental assessment for 2,3-butanediol production from bread waste

Bread waste (BW) is a common food waste in Europe and North America and has enormous potential as a biorefinery substrate for the sustainable synthesis of various platform chemicals. Our previous work made use of BW for the fermentative production of 2,3–butanediol (BDO). The present work evaluated the economic prospects and environmental consequences associated with the overall processes, handling 100 metric tons BW per day. The comprehensive process design using Aspen Plus and integrated techno-economic and environmental assessment was carried out for two different BW hydrolysis scenarios: acid and enzyme hydrolysis, followed by fermentation and extraction-based downstream BDO separation. The optimal heat exchanger network was designed using pinch analysis, which improved the energy efficiency of the process significantly, with about 10 % savings of BDO production costs. Despite this improvement, the BDO derived from BW was exorbitant (4.2–6.9 $/kg) compared to the market price (3.23 $/kg) due to relatively higher capital investment for the current plant capacity. Further, the process inventory was modelled in SimaPro v9.1.0 to estimate the environmental consequences of these production processes for impact categories, such as global warming (2.63 – 3.19 kg CO2 eq.), marine eutrophication (3.55 × 10-4 – 4.01 × 10-4 kg N eq.), terrestrial ecotoxicity (6.44 – 7.88 kg 1,4 − DCB), etc. Sensitivity and uncertainty analyses were also conducted to establish the reliability of the results. It was found that the enzyme hydrolysis was associated with lower environmental impacts than acid hydrolysis. This comprehensive study can be used as a guideline for developing sustainable BW-based biorefinery in the future.

Data Curation and Cartographic Narratives on Indigenous Circulation Networks in the Orinoco Region: Methodological Reflections on the Project Inventar Colombia

Inventar Colombia: una mirada desde el Orinoco is a digital research project that seeks to reconstruct aspects of the geographic imagination, forms of relationship with nature and its resources, of at least 15 Indigenous groups that inhabited the Orinoco region between the fifteenth and eighteenth centuries. Responding to the limits to what we can know in the archive about the ways in which various Indigenous groups inhabited and conceived the territory, we carried out a process of curation and extraction of geospatial data in historical and archaeological sources. We identified some patterns of territorial occupation and exchange networks of the multiplicity of Indigenous communities that have inhabited the Orinoco region. From iterations for the construction of maps with QGIS and typical GIS conventions, we explored other forms of visualization and narrative construction to deploy the arguments of the research on the web. We proposed a CSM-free web interface developed with JavaScript and open-source libraries and developed a set of cartographic narratives.

ITraNet: A Web-Based Platform for integrated Trans-Omics Network Visualization and Analysis

Abstract Motivation Visualization and analysis of biological networks play crucial roles in understanding living systems. Biological networks include diverse types, from gene regulatory networks and protein–protein interactions to metabolic networks. Metabolic networks include substrates, products, and enzymes, which are regulated by allosteric mechanisms and gene expression. However, the analysis of these diverse omics types is challenging due to the diversity of databases and the complexity of network analysis. Results We developed iTraNet, a web application that visualizes and analyzes trans-omics networks involving four types of networks: gene regulatory networks; protein–protein interactions; metabolic networks; and metabolite exchange networks. Using iTraNet, we found that in wild-type mice, hub molecules within the network tended to respond to glucose administration, whereas in ob/ob mice, this tendency disappeared. With its ability to facilitate network analysis, we anticipate that iTraNet will help researchers gain insights into living systems. Availability iTraNet is available at https://itranet.streamlit.app/. Supplementary information Supplementary data are available at Bioinformatics Advances online.

Qualitative Interviews with Stakeholders in Herbal Pharmacovigilance and Recommendations for Best Practices to be Applied Worldwide.

The use of herbal products globally is substantial, but varying definitions and regulatory frameworks have led to differences in their status as medicinal products and in approaches to monitoring their safety. This article explores the current landscape of herbal pharmacovigilance, drawing insights from interviews with global experts in the field, and offers recommendations for best practices to enhance the safety and benefit-to-harm balance of herbal products. This study comprised semi-structured interviews with members of the International Society of Pharmacovigilance-Herbal and Traditional Medicines Special Interest Group and the Nutrivigilance Information Exchange Network, recruited using purposive sampling. Data were stored and coded using NVIVO® and analysed thematically using a qualitative inductive approach. Sixteen participants from 11 countries were interviewed, revealing diverse regulatory approaches and challenges in herbal pharmacovigilance. Key themes included legal status, awareness, identification and coding of herbal products, pre-/post-marketing product control, reporting of adverse drug reactions, causality assessment and signals of herbal products. This study yielded five general recommendations to further improve herbal pharmacovigilance worldwide. This study offers an overview of the global landscape of herbal pharmacovigilance, highlighting challenges in monitoring herbal products and presenting universal recommendations. These recommendations encompass increasing awareness, enhancing education and improving legislative frameworks. Given the growing use of herbal products, the implementation of strong pharmacovigilance practices is crucial to ensure consumer safety.

Equilibrium modelling of steam gasification of PKS system and CO2 sorption using CaO: A digitalized parametric and techno-economic analysis

The conversion of palm oil waste into energy can complement the energy mix with renewable energy and bring economic benefits to the palm oil industry. A process simulation model for palm kernel shell (PKS) steam gasification for H2-enriched syngas with the integration of CO2 capturing using CaO has been investigated using Aspen Plus V10®. Techno-economic and energy analyses have also been conducted to identify energy-saving opportunities for commercialization. The effect of process variables, including reactor temperature (600–800 °C), Steam/PKS ratio (0.5–2 wt/wt), and CaO/PKS ratio (0–1.5 wt/wt), have been determined, with the predicted results compared to the reported experimental data. H2 concentration has been increased with 76–78 vol% with the temperature elevation from 650 to 750 °C. Additionally, a substantial increase in H2 content from 68 to 72vol% was observed when the steam flow rate was increased from 0.5 to 1.5. Conversely, the CO2 concentration decreased from 25 to 8vol% as the adsorbent ratio was raised from 0.5 to 1.5. The techno-economic analysis showed that the capital investment is $4.11 million, and the operating cost is $3.89 million per year, which is also very high due to the high raw material costs. In the case of energy, saving that 3.03 and 1.513 Gcal/hr can be saved in terms of utilities and gas cooling that economized the process which shows that utilization of these in heat exchange networks can significantly reduce costs, with up to 78 % savings in heat exchanger capital and 35 % in total energy consumption. The energy potential could be harnessed through the digitalization of the process.

Utilization and exchange of jade in western China during the late Longshan Era (2300∼1800 BC): Evidence from Lajia site, Minhe County, Qinghai Province

During the Longshan Era, the production and use of jade, including bi-discs, cong-tubes, axes, and other artifacts, were prevalent in several regions situated along the middle and upper reaches of the Yellow River. The exchanges and interactions between them have been discussed by many scholars. Among these societies that valued jades, Ganqing region of Qijia Culture is regarded as a significant source of some valuable jade materials like nephrite. The non-destructive testing of jade artifacts excavated from the Lajia site, a central settlement of the Qijia culture, revealed a comparatively high proportion of nephrite, as well as a rich variety of materials. This demonstrates the acknowledgment and utilization of jade materials, particularly the valuable nephrite in the surrounding region. The availability of jade materials and uncomplicated jade processing created the conditions for household production of jade. Needs for ritual and exchange are considered as potiential driving force behind such production. Evidences of producing and using amazonite artifacts and trumpet-shaped tubes suggests long-distance exchange and influence of jade artifacts/materials. The circulation of nephrite materials may also have been embedded in this network of exchange.

Integration of distributed PV into smart grids: A comprehensive analysis for Germany

Modern smart grids typically combine physical and communication networks for efficient information exchange and innovative applications. Aligned with digitalization and advancements in smart grids, the integration of photovoltaic (PV) systems comprises a variety of regulatory and technological aspects. However, no previous study has conducted an extensive and systematic analysis of the PV-grid integration framework, particularly for one country. To fill this gap, this paper uses Germany as an example to present a comprehensive, state-of-the-art analysis of integrating distributed PV systems into smart grids, focusing on the regulation and technical implementation of the German Smart Meter Infrastructure and PV control interfaces. Starting from a standardization perspective, this analysis utilizes the Smart Grid Architecture Model to identify crucial roles, components and processes specifically in Germany. Furthermore, it outlines the current implementation of PV integration into distribution networks at a national level. The results of this study show the overall complexity of PV integration in the smart grid context, confirm the feasibility of the German integration approach, and highlight the necessity of deploying standardized information models and communication technologies. These key findings can help market participants with different roles to identify potential technical bottlenecks or other critical points in the regulation and technical implementation. For instance, the proposed in-depth analysis framework provides an orientation for characterizing the PV integration or, more generally, the grid integration scenario of renewables in other countries.

EFSA's activities on emerging risks in 2022

Abstract The main objectives of EFSA's activities on emerging risks encompass: (i) conducting activities to identify emerging risks; (ii) developing and improving emerging risk identification (ERI) methodologies and approaches; and (iii) communicating identified issues and risks. The outcome of these activities equips EFSA to anticipate forthcoming challenges in the continuously evolving landscape of risk assessment. EFSA networks of knowledge contributing to the emerging risks identification activity include the Emerging Risks Exchange Network (EREN), the Stakeholder Discussion Group on Emerging Risks (StaDG‐ER), EFSA's scientific units, the scientific panels, the Scientific Committee and their working groups. The current technical report summarises the activities of all groups involved in the emerging risk identification procedure, the issues identified in the course of 2022, the emerging risk identification methodologies being developed, and the collaborative activities. In total, 13 potential emerging issues were discussed in 2022 and two were concluded to be emerging risks. The potential issues were classified according to the hazard. The year 2022 marks a turn in EFSA's activities on emerging risk identification. To achieve strategic objective no. 2 ‘Ensure preparedness for future risks analysis needs’ of the EFSA Strategy 2027, a new process ‘Environmental scanning and strategic options definition’ has been developed. The process adds to the already existing emerging risks analysis workflow a second workflow that is more forward‐looking, to deal with horizon scanning in the areas of food and feed safety, plant health and animal health. Similarly to the emerging risks analysis workflow, the new workflow for horizon scanning strongly relies on partnership to be prepared for future challenges, build resilience, and proactively shape the future in a one‐health approach.

Navigating inter-team competition: How information broker teams achieve team innovation.

Organizations are increasingly using teams to stimulate innovation. Often, these teams share knowledge and information with each other to help achieve their goals, while also competing for resources and striving to outperform each other. Importantly, based on their industry, the nature of work, or prior history, some teams may face more competition from peer teams than others. Our research examines how teams' competitive relations with other teams in the organization operate in tandem with their collaborative inter-team information exchange relations in impacting their innovation. Using two studies-a field study of 73 knowledge-intensive teams in high-tech engineering firms and a team-based network experimental study of 162 teams-we find that a high degree of overall competition with many peer teams reduces a focal team's ability to acquire and utilize diverse knowledge from these teams (i.e., inter-team knowledge integration), thereby hindering team innovation. However, applying insights from network structural hole theory, we find that when a focal team occupies a brokerage position in the inter-team information exchange network, this can help buffer the effects of competition in getting access to knowledge resources from other teams, thus enabling their innovation. Additionally, we find that focal broker teams' dealmaking and network obstruction behaviors explain these effects. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Evaluating synthetic fuel production: A case study on the influence of electricity and CO2 price variations

To combat climate change, we need to reduce emissions from the transport sector. Synthetic fuels are a long-term solution for aviation, maritime and heavy machinery. Large-scale use requires cost-effectiveness, efficient production and resilience to price changes. In this case study, we simultaneously optimize the cell voltage of the solid oxide electrolysis cell, the heat exchanger network and the heat supply of a PtL-plant. PtL-efficiency and production costs are used as objectives to generate multiple Pareto fronts for future price scenarios. The results show that the sensitivity to price changes has different impacts on design and operating parameters, which can lead to unattractive solution domains in the Pareto front. Currently, synthetic fuels can be produced at 1.83–2.36 €/kg. In the best case, at 1.42–1.97 €/kg and 3.88–4.28 €/kg in the worst case. This paper supports decision-makers in planning PtL-plants to ensure sustainable synthetic fuel availability on a global scale.

Maritime hinterlands and interregional interaction at Late Antique Kekova Adası, Türkiye

How do resource-poor island communities develop networks to ensure their supply of foodstuffs and basic commodities? The growth of the Late Antique (5th-7th century CE) town at Kekova Adası on the southern Turkish coast of Lycia offers an instructive case study. Underwater survey along the town’s harbor front yielded large quantities of amphoras, utilitarian and fine pottery, and ceramic building materials that testify to local consumption and transshipment activities on the island. The origins of these materials serve as proxy for the networks of exchange that underpinned life on Kekova Adası. Yet because many of the most common amphora and other pottery types were produced over wide areas of many hundreds of kilometers of coast in Late Antiquity, ceramic petrography is necessary to determine or more precisely define the origins of these materials and, in turn, the shape of the networks through which they moved. The results reveal that the inhabitants of Kekova Adası developed a hinterland for supply by sea that encompassed the coastal plain around Limyra some 40 km to the east as well as, seemingly, across the open sea to the southwest corner of Cyprus. While most of the bulk processed agricultural goods (particularly wine and oil) carried in these amphoras, and the ceramic building materials and other imported wares, derived from these two regions, this hinterland also intersected with larger networks of exchange that brought amphoras as well as fine and cooking wares from across the Levant, Cilicia, the east Aegean, and the northeast Peloponnese. This pattern articulates the integration and mutual interdependence of Kekova Adası’s local network with the particularly busy interregional route that supplied major urban centers and the state during this period. In the process, the case study highlights the necessity of ceramic petrography as a means of precisely reconstructing such networks.

Replicated multistage interconnection networks: QoS evaluation for parallel and distributed computing

Introduction to big data becomes very important with dealing in high-performance parallel distributed computing, especially in those systems where communication among a number of processors is required. The current paper takes into consideration different topologies for the Shuffle Exchange Network (SEN) in order to attain optimal data transfer among such scenarios. SEN topologies are a key feature in connecting several processors and implementing the data transfer among them where a single processor fails to handle the load. The study hereby reports in the performance, reliability, and cost analysis of these topologies. These topologies, some of which are advocated to have better performance in many studies, include replicated networks. Our research demystifies claims made in earlier papers that replicated networks have inflated reliability and higher costs due to their additional links. Researchers are therefore guided on accurate performance data that will lead them to make optimum choices of SEN topologies for targeted applications. These findings further highlight that the trade-offs between reliability and cost must be carefully considered during network design so as to arrive at better results for big data communication and computation in parallel and distributed systems. This work provides important insights into the correct evaluation of SEN topologies, helping to correct the misleading facts and to have better network selection for various real-time application realizations.

Muonium state exchange dynamics in n -type GaAs

Muonium (Mu), a pseudoisotope of hydrogen with a positively charged muon in place of the proton, takes the form Mu+,0,− (like isolated hydrogen, i.e., H+,0,−) in semiconductors. The specifics of the charge state depend on the local electronic environment of the host. After initial muon implantation, generated Mu centers interact with free charge carriers and electronic spins, transition between sites, and form a dynamic network of state exchange. We identified the model of Mu dynamics in n-type GaAs using the density matrix simulation method and photoexcited muon spin spectroscopy technique. Fitting to the dark and illuminated μSR data provided transition rates between Mu states, revealing the underlying mechanisms at play between the Mu centers (cf. isolated H) and the host. Deduced capture/scattering cross sections of the Mu states reflected the microscopic dynamics of Mu. Illumination studies enabled us to measure interactions between Mu and minority carriers, which would be unavailable in dark measurements without heating. The methodology developed in this study may be applied to other semiconductor systems for a deeper understanding of the Mu state exchange dynamics. Published by the American Physical Society 2024

Intelligent construction and optimization based on the heatsep method of a supercritical CO2 brayton cycle driven by a solar power tower system

The current progress in tower-based solar thermal concentrators and receivers enables achieving temperatures within the required range of 500–700 °C for the S–CO2 Brayton cycle. Within this temperature range, the efficiency of the S–CO2 Brayton cycle exceeds that of conventional steam power cycles. This study applies the S–CO2 Brayton cycle to concentrated power generation systems, emphasizing structural and parameter optimization. By utilizing the operational parameters of tower-based solar thermal power generation as boundary conditions and maximizing specific power as the optimization objective, various configurations derived from a maximum of two fundamental cycles are systematically enumerated. Subsequently, an intelligent algorithm optimizes the power cycle flow and parameters for each structure, further optimizing the heat exchanger network. The findings reveal that the optimized configuration shares a common heating and cooling process. This optimization yields a specific power increase of 14.62 kJ/kg compared to the reference case, indicating a 13.26 % enhancement. Additionally, the cycle efficiency improves to 47.45 %, marking a 28.52 % increase. The overall system efficiency for the solar power tower system reaches 32.03 %, with an exergy efficiency of 32.19 %.

A novel polygeneration process integrated into a gas turbine cycle toward an environmentally friendly framework; Application of a comprehensive 4E study

In this study, a new environmentally friendly polygeneration scheme is proposed in arrangement with a gas turbine cycle. In order to investigate the proposed system, parametric research is conducted in conjunction with the energy, exergy, economic, and environmental assessments (4E study). The simulation is done in the Aspen HYSYS software. According to the design condition results, the total energy efficiency and exergy efficiency, thermoeconomic indicators such as total unit cost of product and total product cost, as well as the waste heat recovery ratio in the heat exchanger network of the evaporator, are 57.81 %, 63.47 %, 25.12 $/GJ, 0.1019 $/kWh, and 49.67 %, respectively. In addition, it is determined that the total exergy destruction rate and the exergy destruction intensity for the proposed process are 204470 kW and 1.33 kWD/KWP, respectively. The gas turbine cycle with a share of 60 %, exhibits the highest irreversibility. Based on economic estimates, the project requires a total investment of $636209804. In addition, considering an annual income of 159850224 $, the payback period is 3.98 years. Lastly, the environmental evaluation indicates that the proposed process has a carbon footprint equal to 0.356 kgCO2/kWh and a total carbon dioxide emission of 67241.36 kg/h.