Exchanger Network Research Articles

Leveraging the OECD Framework to Create Policies That Enable Eco-Innovation: A Case study of Neom

Amid escalating urbanization worldwide, cities confront the imperative to reconcile economic growth and environmental sustainability. This study employs a comparative analysis to evaluate the applicability of the Organization for Economic Cooperation and Development’s (OECD) seminal eco-innovation policy framework within Saudi Arabia’s emergent Neom City. The OECD framework delineates a robust policy ecosystem encompassing economic incentives, regulatory standards, market facilitation mechanisms, and knowledge exchange networks to catalyze eco-innovation. Initial benchmarking reveals lacunae within Neom’s extant sustainability planning, including limited financial incentives for green technology adoption and nascent sustainability education programs. Targeted integration of OECD prescriptions could potentiate Neom’s eco-innovation across multifaceted domains spanning renewable energy integration, energy efficiency, green infrastructure, and sustainable mobility. Urban policymakers can operationalize elements of the OECD’s model to align Neom’s development objectives with ecological sustainability, propelling its ambitions to manifest as an pioneering sustainable city. This research proffers strategic insights that can enable urban governance actors worldwide to leverage policy architectures to synergize economic growth and sustainability.

Comparison of signal processing methods considering their optimal parameters using synthetic signals in a heat exchanger network simulation

Plant sensor data contain errors that can hamper process analysis and decision-making. Those dataset are not used to their full potential due to the complexity of their processing. This paper addresses these challenges by comparing popular data processing techniques based on their ability to process sensor data, all that while using optimal parameters. The latter are obtained for all approaches using an algorithm that performs a parametric sweep. The performance of Kalman filter, exponential weighted moving average filter, short-time Fourier transform, and wavelet transform to process synthetic flow and temperature signals from a heat exchanger network simulation is quantified given two criteria: signal-to-noise ratio (SNR) and root mean square error (RMSE). It is found that most of the time, wavelet transform showed the highest RMSE reduction and SNR improvement; the wavelet transform can effectively filter signals from distinct variables from a heat exchanger network simulation when optimal parameters are selected.

Energy saving in Cu-Cl thermochemical cycle for green hydrogen production: Use of heat integration approach and simulation tools

Hydrogen, both green and blue, is a crucial fuel as it carries energy from sustainable sources and has no impact on global warming. Thermochemical methods for green hydrogen generation are promising alternative technologies to previous technologies for the commercial-scale generation of hydrogen gas without fossil fuel. In the present work, ICT-OEC six-step copper-chlorine (Cu-Cl) thermochemical cycle is explored, its efficiency is investigated using the Aspen Plus simulation software, and probable efficiency enhancements are addressed. Using the Aspen energy analyzer, different design configurations for the heat exchanger network were proposed, and thermal management within the cycle was studied. The implementation of thermal management strategies yielded a substantial enhancement in the efficiency of the Cu-Cl cycle, elevating it from 38.68% to 51.54%. The comparative analysis of the 6-step Cu-Cl cycle with other 3-, 4-, and 5-step cycles revealed that the 4-step Cu-Cl cycle (UOIT-CERL, Canada) exhibited higher energy efficiency. However, the 6-step Cu-Cl cycle shows greater promise for commercialization.

Temperature zone diagram method for designing the total site exchanger network

Temperature zone diagram method for designing the total site exchanger network

Extensive pedigrees reveal the social organization of a Neolithic community.

Social anthropology and ethnographic studies have described kinship systems and networks of contact and exchange in extant populations1-4. However, for prehistoric societies, these systems can be studied only indirectly from biological and cultural remains. Stable isotope data, sex and age at death can provide insights into the demographic structure of a burial community and identify local versus non-local childhood signatures, archaeogenetic data can reconstruct the biological relationships between individuals, which enables the reconstruction of pedigrees, and combined evidence informs on kinship practices and residence patterns in prehistoric societies. Here we report ancient DNA, strontium isotope and contextual data from more than 100 individuals from the site Gurgy 'les Noisats' (France), dated to the western European Neolithic around 4850-4500 BC. We find that this burial community was genetically connected by two main pedigrees, spanning seven generations, that were patrilocal and patrilineal, with evidence for female exogamy and exchange with genetically close neighbouring groups. The microdemographic structure of individuals linked and unlinked to the pedigrees reveals additional information about the social structure, living conditions and site occupation. The absence of half-siblings and the high number of adult full siblings suggest that there were stable health conditions and a supportive social network, facilitating high fertility and low mortality5. Age-structure differences and strontium isotope results by generation indicate that the site was used for just a few decades, providing new insights into shifting sedentary farming practices during the European Neolithic.

Food globalization in southern Central Asia: archaeobotany at Bukhara between antiquity and the Middle Ages

The Silk Road is a modern name for a globalization phenomenon that marked an extensive network of communication and exchange in the ancient world; by the turn of the second millennium AD, commercial trade linked Asia and supported the development of a string of large urban centers across Central Asia. One of the main arteries of the medieval trade routes followed the middle and lower Zarafshan River and was connected by mercantile cities, such as Samarkand and Bukhara. Bukhara developed into a flourishing urban center between the fourth and sixth centuries AD, served as the capital of the Samanid court between AD 893 and 999, and remained prosperous into the Qarakhanid period (AD 999–1220), until the Mongol invasion in AD 1220. We present the first archaeobotanical study from this ancient center of education, craft production, artistic development, and commerce. Radiocarbon dates and an archaeological chronology that has been developed for the site show that our samples cover a range between the third and eleventh centuries AD. These samples from Bukhara represent the richest systematically collected archaeobotanical assemblage thus far recovered in Central Asia. The assemblage includes spices and both annual and perennial crops, which allowed Sogdians and Samanids to feed large cities in river oases surrounded by desert and arid steppe and supported a far-reaching commercial market in the first millennium AD.

Synthesis and Retrofit of Multiperiod Heat Exchanger Networks Considering Heat Transfer Enhancement and Environmental Impact

Heat transfer enhancement has been used to achieve lower heat transfer area and reduced utility requirements in heat exchanger network synthesis problems involving retrofit. This paper presents a technique for implementing heat transfer enhancements in both grassroot and retrofit heat exchanger network synthesis problems involving multiperiod operations. For the grassroot scenario, the approach adopted involves extending the stage-wise superstructure model for multiperiod heat exchanger network synthesis to accommodate various options of tube-side and shell-side heat transfer enhancement techniques. The extended model is then applied to a retrofit scenario using the reduced superstructure synthesis approach. The results obtained demonstrate the benefits of heat transfer enhancement through reduced operating costs in the grassroot and retrofit scenarios. For the grassroot scenario, the operating and capital costs obtained in this paper are 12.3% and 20% lower than solutions obtained using conventional non-enhanced synthesis methods, while for the retrofit scenario, solutions which compare favourably with literature solutions, and which has the potential to be more environment friendly by virtue of lower energy utilisation, are obtained.

A Systematic Heat Recovery Approach for Designing Integrated Heating, Cooling, and Ventilation Systems for Greenhouses

Ventilation heat loss is one of the most important factors contributing to energy performance of greenhouses. This paper suggests a systematic method based on dynamic pinch analysis (PA) to design an integrated heating, cooling, and ventilation system that uses ventilation waste heat in a cost-effective and energy efficient way. A heat recovery system including an air handling unit, borehole thermal storage, and a heat pump is proposed to investigate all heat integration scenarios for an entire year. In the first step, the heat integration scenarios are reduced to a few typical days using a clustering technique. Then, a generic methodology for designing a heat exchanger network (HEN) for a dynamic system, ensuring both direct and indirect heat recovery, is presented and a set of HENs are designed according to the conditions of typical days. Afterwards, the best HEN design is selected among all design alternatives using a techno-economic analysis. The whole procedure is applied to a commercial greenhouse and the best HEN configuration and required equipment sizes are calculated. It is shown that the best-performing design for the greenhouse under study produces primary energy savings of 57%, resulting in the shortest payback period of 9.5 years among all design alternatives.

Estimating parameters of plate heat exchanger for condensation of steam from mixture with air as a component of heat exchanger network

The condensation of vapours in the presence of non-condensable gas is happening in a number of industries. Its efficient realisation must be considered in optimisation of Heat Exchanger Networks (HENs) to increase efficiency of energy usage. In these processes, Plate Heat Exchanger (PHE) with enhanced heat and mass transfer can be effectively used. The method of preliminary selection of the PHE heat transfer area, plate size and corrugation geometry is proposed for the case of steam condensing from its mixture with air. The method uses the developed earlier one-dimensional mathematical model, modernized for PHE consisting from commercially produced plates. The heat transfer area of PHE is minimised by proper selection of plate sizes and geometrical characteristics of its corrugation. The optimisation variables are the corrugation angle to the main flow direction inside PHE channel, the corrugations depth and the length of plate. The case study illustrates the application of the method in case of utilisation low grade heat from exhaust gases after process of drying by superheated steam. The method is implemented as a computer program which can be included as a Dynamic Link Library module in software for HEN optimisation.

Waste heat recovery potential in the thermochemical copper–chlorine cycle for hydrogen production: Development of an efficient and cost-effective heat exchanger network

With the finite nature of fossil fuel resources and related environmental issues, it is necessary to replace fossil-fuel-based hydrogen production methods with more sustainable ones. For the clean production of hydrogen, the copper-chlorine (Cu–Cl) thermochemical cycle is a favorable choice. However, internal waste heat recovery of the cycle is essential to improve the efficacy of the system. In this paper, the waste heat recovery potential of the four-step Cu–Cl cycle is investigated, to support the design of a new cost-effective and high-performance heat exchanger network. Pinch analysis is executed to find the optimum rates of cold and hot utilities for this cycle. Three heat exchanger network cases are investigated which include case 1, without heat recovery; case 2, with 16 heat exchangers; and case 3, with 11 heat exchangers. The effect of varying design parameters on the energy system's efficiency and cost-related parameters are also explored here. Based on the pinch analysis results, the minimum heating and cooling and the maximum recoverable heat, on a normalized basis, are 333.3 kJ/mol H2, 76.9 kJ/mol H2, and 134.4 kJ/mol H2, respectively. Moreover, for cases 1, 2, and 3 the thermal efficiencies are calculated as 33.3%, 41.1%, and 40.5%, respectively. Additionally, it is observed that, when the thermal energy of the cycle is supplied from a solar power tower plant, the levelized cost of hydrogen for case 1 is 9.6 $/kg H2, for case 2 is 7.9 $/kg H2, and for case 3 is 7.8 $/kg H2.

Petrographic and geochemical analyses of Late Bronze and Iron Age pottery from Arslantepe (Malatya, Turkey): insights into the local organization of the production and extra-regional networks of exchange

In this paper, we analyzed Late Bronze and Iron Age pottery assemblages from the site of Arslantepe (Malatya, eastern Turkey) by utilizing a combination of thin-section petrography and X-ray wavelength dispersive fluorescence techniques. Following an introduction to the site and an overview of the archeological and historical evidence, the analysis is presented, and the outcomes discussed in the wider framework of the Syro-Anatolian and eastern Mediterranean regions. The results show elements of both continuity and change over the second millennium and until the beginning of the first millennium BC. On a local level, the use of volcanic-based recipes for the production of painted vessels represents the most striking element of continuity. In contrast, noteworthy elements of changes relate to an increased exploitation of geological deposits south of Arslantepe and the standardization of paste recipes for cooking pots. Remarkable results also pertain to extra-regional exchanges: The Late Bronze Age Red Lustrous Wheel-made Ware found at the site is imported from Cilicia, while the wares of foreign tradition from the Middle Iron Age levels are mostly locally produced.

A novel transfer matrix-based method for steady-state modeling and analysis of thermal systems

Performance analysis and optimization of thermal systems are unprecedentedly crucial in pursuing higher energy efficiency. However, the precise modeling and high-efficiency calculation of modern, complex thermal systems are still challenging. Here we present a transfer matrix-based system modeling method to tackle these challenges. The transfer matrix of heat exchangers is defined to describe the temperature mapping relation between inlet and outlet nodes. Heat-work conversion devices are described by the working fluid temperature variation. The system modeling follows a three-step procedure: (1) building system transfer matrix by aggregating component models; (2) separate given and unknown node temperatures by removing redundant rows and columns in the system transfer matrix; (3) rearrange the reduced system transfer matrix to calculate internal and outlet node temperatures. The constructed system model does not introduce unnecessary simplifications and describes the system’s nonlinearity accurately. The proposed modeling method is first presented and validated on a parallel-series and a multi-loop heat exchanger network. Numerical results with both constant and varying fluid properties confirm the method’s validity. Case studies on three thermodynamic systems further validate the method’s capability and efficiency. The proposed method is finally compared with conventional modeling methods and heat current method to highlight its features and advantages.

Closed-Loop Energy Flow Redistribution for Optimal Operation of Heat Exchanger Networks

Closed-Loop Energy Flow Redistribution for Optimal Operation of Heat Exchanger Networks

Unveiling the Dynamics of Millet Spread into Xinjiang: New Evidence of the Timing, Pathways, and Cultural Background

Xinjiang, in Northwestern China, was a key point in the prehistoric trans-Eurasian network of exchange and played an important role in facilitating the dispersal of crops across Eurasia. Millet crops were first cultivated and used ca. 10,000 years ago in Northern China, from where they spread via different routes, leaving intriguing traces in various sites across Xinjiang. This paper presents the latest data on millet in Xinjiang. By employing a multidisciplinary approach, including radiocarbon dating, archaeobotanical evidence, and carbon isotope datasets, this study explores potential routes by which millet entered Xinjiang and traces its expansion from the third millennium BC to the 10th century AD. The research highlights the significant role of millet in shaping the ancient economies and cultures of Xinjiang and Central Asia, while also underscoring the importance of further investigation to uncover the complex pathways of its dispersal across Eurasia.

Animal exploitation in Southwestern Iberia at the end of the second millennium BCE: insights from the Late Bronze Age of Outeiro do Circo (Beja, Portugal)

The Late Bronze Age was an important phase in European Prehistory but our understanding of its regional dynamics is unequal. Relevant knowledge of the peopling and material culture of Southwestern Iberia between 1170 and 730 BCE exists, but the exploitation and management of animals remain largely uncharacterized. We generally lack the taphonomical data that could allow for an in-depth understanding of faunal assemblages’ formation, with relevance for the description of depositional environments if paired with relative and absolute chronologies. We present two new absolute dates for the Outeiro do Circo Late Bronze Age and a zooarchaeological and taphonomical analysis of the total recovered faunal assemblage. Caprine, swine, and bovine primary and probably secondary products were of importance, with the hunting of red deer and wild boar being complementary. Other species such as leporids, equids, canids and several molluscs were recovered. The latter are mostly intrusive terrestrial gastropods but the scarce presence of scallops and peppery furrow shells can also relate to exchange networks. Taphonomical indicators of the butchering and consumption of animals and the secondary access by a large canid are well attested in the assemblage, as well as the culinary and non-culinary thermo-alteration of animals’ bones.

Robinson Crusoe in the Pacific: REFUGIO by Roger Palmer and the Marxian theory of economic character masks

ABSTRACT Robinson Crusoe is among the world’s most mythologized fictional characters. As homo economicus, economic man, Crusoe is a byword for rugged individualism. Crusoe has been linked to the emergent bourgeois individual, and this role offers a way to reconsider, after 300 years of circulation, an alternate economic reading of the character. This article rereads Crusoe’s role in Marx’s theory of commodity fetishism, prompted by an art installation, REFUGIO – after Selkirk, after Crusoe by Roger Palmer, which explores a visually doubled figure of Crusoe relocated to the Pacific Ocean. This trope of doubling is reinterpreted with Marx’s concept of “economic character masks” and J.M. Coetzee’s postcolonial re-imagining of the Crusoe story, Foe, showing that Crusoe’s economic character mask continues to operate in the capitalist world while his body is absent. Homo economicus is a fiction that obscures the capitalist individual’s imbrication with globalizing networks of exchange, accumulation, and exploitation.

Production and Exchange Networks of Cord-marked Pottery from Oinam Village in Manipur, Northeast India: An Ethnoarchaeological Perspective

ABSTRACT The production of cord-marked pottery in the village of Oinam, located in the Indian state of Manipur, is practiced by the women potters of the Poumai Nagas, an Indigenous Tibeto-Burman ethnic community. A two-week ethnographic study was conducted in 2021 among the Poumai Nagas to document the dynamics of the production process and oral accounts of the potters and other villagers including residents from the non-pottery-producing Naga villages. While there is decreasing demand for earthen vessels today, the survey's outcome suggests a large exchange network and interaction in the Naga Hills centered on the pottery of Oinam. This network facilitated trade and fostered political and economic alliances among the Naga communities. The study also supports the claim of regional exchange networks in the region in the past and further documents that cord-marked pottery formed a significant trade item.

Regression of binary network data with exchangeable latent errors

AbstractUndirected, binary network data consist of indicators of symmetric relations between pairs of actors. Regression models of such data allow for the estimation of effects of exogenous covariates on the network and for prediction of unobserved data. Ideally, estimators of the regression parameters should account for the inherent dependencies among relations in the network that involve the same actor. To account for such dependencies, researchers have developed a host of latent variable network models; however, estimation of many latent variable network models is computationally onerous and which model is best to base inference upon may not be clear. We propose the probit exchangeable (PX) model for undirected binary network data that is based on an assumption of exchangeability, which is common to many of the latent variable network models in the literature. The PX model can represent the first two moments of any exchangeable network model. We leverage the EM algorithm to obtain an approximate maximum likelihood estimator of the PX model that is extremely computationally efficient. Using simulation studies, we demonstrate the improvement in estimation of regression coefficients of the proposed model over existing latent variable network models. In an analysis of purchases of politically aligned books, we demonstrate political polarization in purchase behavior and show that the proposed estimator significantly reduces runtime relative to estimators of latent variable network models, while maintaining predictive performance.

Using the Progressive Design Method in higher education: An analysis of cohesion, collaboration and inclusion dimensions

Many cognitive benefits for learning have been highlighted in the literature, due to peer feedback, but the relational aspects of this way of working, when it is implemented with groups of students, have been little investigated. This study aims to analyze some relational aspects of the use of peer feedback in the university context, considering in particular how the cohesion in the network of exchanges, the level of collaboration and inclusion of students, change during an activity carried out with a method based on peer feedback called Progressive Design Method. Eighteen undergraduate students participated in the study and worked in teams to develop projects in successive phases, each of which involved peer feedback in an online environment, Knowledge Forum. The results showed an increase in the values of the three dimensions (cohesion, collaboration and inclusion) in the first phases of work and a decrease in the last phase. The implications of the study focus on the possibility of creating collaborative learning environments in universities based on this method of work.

세계화 시대 한국 내몽골고학력자 취업이민에 대한 사례 연구

In recent years, highly educated people have been immigrating depending on the demand and supply of the labor markets in their countries of origin and countries of destination under the influence of globalization. Brain drain and brain gain lead to the building of a network for academic exchange between the country of origin and the receiving country influencing beyond the limit within the boundary of each country. To test this hypothesis, in-depth interviews were conducted in this study with highly educated Mongolians who immigrated to South Korea. The themes from a case study were analyzed. First, highly educated Mongolians came to South Korea as they received South Korea-Mongolia government scholarships. They quit their job in Mongolia to study abroad, or decided to study abroad after graduating a high school. Their studying-abroad tends to be extended to employment-based immigration in South Korea. Since Mongolian society has barely utilized the capabilities of highly educated people who had studied abroad, the rate of brain drain is high. This is due to the lack of job opportunity for this population, the low demand of highly skilled science and technology workforce, and the low recognition of the economic value of knowledge workers. Second, South Korean society is actively taking advantage of brain gain by attracting international students and allowing employment-based immigration for these students to complement the decreasing South Korean highly educated population. In South Korea, Mongolian college graduates and postgraduate degree holders work in universities for research or administration, start a business based on their expertise, or look for a job. Third, beyond pursuing employment in South Korea, Mongolian college graduates and postgraduate degree holders in South Korea lead the academic exchange between South Korea and Mongolia by contributing to leading research collaborations, and the building and activation of academic network through maintaining cultural and social exchange. From a transnational perspective, this study identified that the brain drain of Mongolia has led to the building and activation of a new academic network between South Korea and Mongolia, beyond the brain gain in South Korea.