Integral Solution Research Articles

Multi-DG qZSI based grid tied inverters

The increasing adoption of distributed generation (DG) systems, driven by their numerous advantages, has led to a growing utilization of hybrid systems. Multilevel converters have emerged as essential components in power electronics applications, offering benefits such as harmonic reduction. However, designing effective control strategies for multilevel inverters presents challenges. This paper proposes a multi-DG quasi-Z-Source Inverter (qZSI) designed with a cascaded H-bridge controller. The incorporation of qZSI in the system enhances reliability and component safety while enabling the implementation of additional shoot-through control. This feature facilitates the balancing of inequalities arising from the two DG sources, thereby improving disturbance rejection. Furthermore, a current control scheme is implemented on the AC side to seamlessly feed active power into the grid without introducing distortions in current injection. Overall, the proposed system addresses key challenges in multilevel inverter design and offers a promising solution for efficient and reliable grid integration of DG systems. This work is thus useful in variety of applications, including electric vehicles and environment sustainability.

Development of an innovative diffraction scattering theory of X-rays and electrons in imperfect crystals.

Fundamental equations describing the X-ray and electron diffraction scattering in imperfect crystals have been derived in the form of the matrix Fredholm-Volterra integral equation of the second kind. A theoretical approach has been developed using the perfect-crystal Green function formalism. In contrast, another approach utilizes the wavefield eigenfunctions related to the diagonalized matrix propagators of the conventional Takagi-Taupin and Howie-Whelan equations. Using the Liouville-Neumann-type series formalism for building up the matrix Fredholm-Volterra integral equation solutions, the general resolvent function solutions of the X-ray and electron diffraction boundary-valued Cauchy problems have been obtained. Based on the resolvent-type solutions, the aim is to reveal the features of the diffraction scattering onto the crystal lattice defects, including the mechanisms of intra- and interbranch wave scattering in the strongly deformed regions in the vicinity of crystal lattice defect cores. Using the two-stage resolvent solution of the second order, this approach has been supported by straightforward calculation of the electron bright- and dark-field contrasts of an edge dislocation in a thick foil. The results obtained for the bright- and dark-field profiles of the edge dislocation are discussed and compared with analogous ones numerically calculated by Howie & Whelan [Proc. R. Soc. A (1962), 267, 206].

Arc Connectivity and Submodular Flows in Digraphs

Let D=(V,A)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D=(V,A)$$\\end{document} be a digraph. For an integer k≥1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$k\\ge 1$$\\end{document}, a k-arc-connected flip is an arc subset of D such that after reversing the arcs in it the digraph becomes (strongly) k-arc-connected. The first main result of this paper introduces a sufficient condition for the existence of a k-arc-connected flip that is also a submodular flow for a crossing submodular function. More specifically, given some integer τ≥1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au \\ge 1$$\\end{document}, suppose dA+(U)+(τk-1)dA-(U)≥τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$d_A^+(U)+(\\frac{\ au }{k}-1)d_A^-(U)\\ge \ au $$\\end{document} for all U⊊V,U≠∅\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$U\\subsetneq V, U\ e \\emptyset $$\\end{document}, where dA+(U)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$d_A^+(U)$$\\end{document} and dA-(U)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$d_A^-(U)$$\\end{document} denote the number of arcs in A leaving and entering U, respectively. Let C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathcal {C}}$$\\end{document} be a crossing family over ground set V, and let f:C→Z\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f:{\\mathcal {C}}\\rightarrow {\\mathbb {Z}}$$\\end{document} be a crossing submodular function such that f(U)≥kτ(dA+(U)-dA-(U))\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f(U)\\ge \\frac{k}{\ au }(d_A^+(U)-d_A^-(U))$$\\end{document} for all U∈C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$U\\in {\\mathcal {C}}$$\\end{document}. Then D has a k-arc-connected flip J such that f(U)≥dJ+(U)-dJ-(U)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f(U)\\ge d_J^+(U)-d_J^-(U)$$\\end{document} for all U∈C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$U\\in {\\mathcal {C}}$$\\end{document}. The result has several applications to Graph Orientations and Combinatorial Optimization. In particular, it strengthens Nash-Williams’ so-called weak orientation theorem, and proves a weaker variant of Woodall’s conjecture on digraphs whose underlying undirected graph is τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au $$\\end{document}-edge-connected. The second main result of this paper is even more general. It introduces a sufficient condition for the existence of capacitated integral solutions to the intersection of two submodular flow systems. This sufficient condition implies the classic result of Edmonds and Giles on the box-total dual integrality of a submodular flow system. It also has the consequence that in a weakly connected digraph, the intersection of two submodular flow systems is totally dual integral.

Passive strategies for climate change mitigation in architectural heritage: the case study of Santa Maria in Trastevere Basilica, Rome

ABSTRACT According to the most recent climate projections, urban settings and historic centres will be affected by considerable increases in temperature extremes and heat waves as a result of climate change. For this reason, the issue of energy efficiency and indoor comfort in historic buildings has become a topic of major interest for the significant number of buildings in the national and European territories. The performance redevelopment of architectural heritage, particularly religious buildings, requires accurate design, through a careful assessment of the occupants’ needs and the historic building’s characteristics, to guarantee adequate levels of thermal comfort and ensure an indoor climate suitable for safeguarding the cultural asset. In this regard, the study investigates, through a data-driven approach and building performance analysis, the indoor comfort level of a religious building in the historical centre of Rome that presents phenomena of excessive indoor overheating. The objective is to identify passive cooling strategies, through the optimization of natural ventilation levels and reduction of surface temperatures of the envelope exposed to solar radiation, in order to propose different design scenarios. The results show how a data-driven process in a digital environment can significantly contribute to the identification of optimal and integrated design strategies and solutions.

Precision calculation of the entrance length for laminar flow of Bingham fluid between parallel plates with yield number from 0 to 1000

An estimate of the entrance length for a Bingham fluid flowing between parallel plates is needed in engineering applications. The dimensionless entrance length is a function of yield number. The primary objective of this study was to construct plots of dimensionless entrance length vs. yield number that could be used by practitioners for a quick estimation of the entrance length in a Bingham fluid entering between parallel plates, in a range of yield numbers from 0 to 1000. Three well-known calculation methods were used. The methods were found to yield mutually consistent results. A secondary objective of this study was to examine the sensitivity of the calculated entrance length to the value of a dimensionless parameter somewhat arbitrary chosen during the calculations. This parameter specifies the dimensionless value of the unyielded core velocity that is accepted as the core velocity at the end of the entrance region. In all three calculation methods, the entrance length was found to have a noticeable sensitivity to the variation of this parameter. The least sensitive method was the one based on the momentum integral solution. The findings necessitate further, more fundamental research on the entrance length in non-Newtonian fluids.

Integrative taxonomic revision of the African thicket rats (Murinae: Grammomys): how genomics decreases the number of currently recognized species

Abstract Thicket rats of the genus Grammomys are partly arboreal rodents distributed across a large part of sub-Saharan Africa. Previous work showed that their highest diversity is in forests and woodlands of Eastern Africa, that the evolutionary history of the genus roughly mirrors the evolution of African forests, and that the currently delimited species (names) do not correspond to major genetic clades. We used thousands of single nucleotide polymorphisms to perform phylogenomic analysis and to delimit genomic pools (i.e. candidate biological species). The resulting molecular operational taxonomic units were then compared with the most comprehensive sets of other available data (mitochondrial DNA variability, ecological requirements, morphology, karyotypes, sequences from the type material, etc.) and used for an integrative solution to the taxonomy of the genus. Our revision delimited seven species, which is less than the 12 recognized in the most recent literature on African rodents. We conclude that the African thicket rats represent a classic example of challenging problems in current integrative taxonomy. It is now relatively easy to obtain genomic data and to delimit candidate species, but it is much more complicated to give them species names using the valid rules of zoological nomenclature.

Validation of the Perceived Community Support Questionnaire for Older Chinese.

Community support has a profound positive impact on older people's health and plays a crucial role in facilitating aging in place. This impact is particularly significant in the Chinese context, where community support can alleviate the pressure on traditional family caregiving. This study translated, adapted, and validated the perceived community support questionnaire (PCSQ) for use with older Chinese. Data for this validation study were collected from a cross-sectional survey of 1,064 Chinese aged 65 years and above. Following the cultural adaptation of the PCSQ-14, confirmatory factor analysis (CFA) was conducted to examine its factor structure. Criterion validity, convergent and discriminant validity, internal consistency reliability, and test-retest reliability of the scale were also assessed. Based on the CFA results, the adapted PCSQ-14 was found to have a 3-factor solution for community integration, community participation, and community organizations. The criterion-related validity was supported by its significant correlation with depression. Convergent and discriminant validity were established, with the internal consistency of the scale being 0.90. The test-retest reliability intraclass correlation coefficient for the scale was 0.78. The adapted version of the PCSQ-14 demonstrated promising psychometric properties in assessing perceived community support in older Chinese. The adapted PCSQ-14 could assist researchers in determining older Chinese adults' perceptions of community support, and could also assist practitioners and policymakers in developing targeted services for older people and allocating resources more effectively.

A European Feminist Foreign and Security Policy? Norm Contestation and Norm Negotiations in the European Parliament

Abstract In 2020, the European Parliament (ep) issued a resolution calling for all European Union (EU) Member States to adopt feminist foreign and security policies, and for a gender-transformative vision in the EU’s own external policy. Drawing on the literatures on negotiations and norm contestation, this article3 asks why the resolution was so progressive. It also asks how we can characterize and explain the nature of the negotiations leading to the resolution. The findings demonstrate a low level of contestation and negotiations mainly characterized by integrative strategies and solutions. The main opponents to the resolution, the populist radical right groups, were more or less absent from the negotiations but opposed by verbal contestation in plenum and through amendments to the text. We find that individual- and organizational level factors have high explanatory power: the gender equality-friendly institutional culture in the ep was further strengthened by the entrepreneurship of two committed rapporteurs.

Efficient method for calculating sound radiation from a circular source in an infinite baffle

The numerically efficient solution describing the sound radiation from a circular source located in a flat, rigid baffle is obtained. For this purpose, a half-space was divided into two subregions coupled through continuity equations. The Helmholtz equation was solved in both subregions. The proposed method can be used for circular baffled sources in the case when fluid–structure interactions are included, as well as for an input from a waveguide or cavity. The validity and numerical efficiency of the presented solution were tested assuming that a clamped circular plate is a source. The numerical simulations show that the results given by the proposed method agree with those given by the known integral solution. The exceptions are the field points at which the integral formulas fail and provide incorrect values of the sound pressure. Hence, the presented formulas can be the only method to perform accurate calculations at troublesome field points. The numerical efficiencies of the obtained formulas and integral ones were compared by estimating the value of the appropriate time ratios. The numerical analysis shows that the proposed method can be used to significantly improve calculations of the sound power and the sound pressure.

Optimal integration and planning of PV and wind renewable energy sources into distribution networks using the hybrid model of analytical techniques and metaheuristic algorithms: A deep learning-based approach

The optimal integration of Renewable Energy Sources (RESs) into distribution networks is crucial for sustainable energy generation. However, existing approaches utilized for optimal RES integration, including metaheuristic and analytical methods, exhibit limitations. Analytical methods are simple to implement, computationally efficient, and able to model power system mechanisms, yet they face scalability issues, making them inefficient for large-scale distribution systems. On the other hand, metaheuristic approaches, while flexible for complex problems, suffer from premature convergence problems, limiting their application in real distribution networks. To address these issues, this paper introduces a novel hybrid model that combines the strengths of analytical and metaheuristic techniques. The proposed model employs a deep learning-based method called bi-directional long short-term memory (B-LSTM) network is utilized to handle the uncertainties associated with the Photovoltaic (PV) and Wind Turbine (WT) generation and load demand. Subsequently, a distinctive analytical multi-objective index-based procedure is developed to minimize the real and reactive energy loss and voltage deviation by analyzing the branch current change caused by the RES penetration in distribution networks. The optimization problem is then solved using the binary particle swarm optimization (BPSO) technique. Importantly, the presented method considers the long-term nature of optimal RES integration and reflects the seasonal impacts of the load and RES output powers. The proposed approach is applied to the IEEE 33-bus test system. The simulation results show that the introduced hybrid model, by addressing the limitations of existing approaches, offers a promising solution for efficient and effective RES integration in distribution systems while requiring low computational effort, thereby advancing the transition towards sustainable energy infrastructure.

Distributed Ledger Approach BlockChain- Based Integrated EHR: A Ethereum Smart Contract Method

Blockchain, on the other hand, is a groundbreaking technology that provides a distributed and Decentralized environment in which nodes in a list of networks can connect to each other without the need for a central authority. It has the potential to overcome the limits of Electronic Health Record (EHR) management and create a more secure, Decentralized, and safer environment for exchanging EHR data. Further, blockchain is a distributed ledger on which data can be stored and shared in a cryptographically secure, validated, and mutually agreed-upon manner across all mining nodes. The blockchain stores data with a high level of integrity and robustness, and it cannot be altered. Electronic health records (EHRs) are digitally saved health records that provide information about a person’s health. EHRs are generally shared among healthcare stakeholders, and thus are susceptible to power failures, data misuse, a lack of privacy, security, and an audit trail, among other problems. The aim of our proposed framework is firstly to implement blockchain technology for EHR and secondly to provide secure storage of electronic records by defining granular access rules for the users of the proposed framework. Moreover, this framework also discusses the scalability problem faced by the blockchain technology in general via use of off-chain storage of the records. This framework provides the EHR system with the benefits of having a scalable, secure and integral blockchain-based solution.

Exploring ICT professional development of experienced female EFL teachers

The integration of Information and Communications Technology (ICT) into language teaching and learning is mandated by the national policy in Indonesia. This study aims to describe 34 experienced female EFL teachers’ experiences ICT professional development.. This study reports on: 1) encouraging and discouraging factors of ICT use for participants, 2) solutions of ICT integration for participants’ professional development, and 3) peers’ perception on participants’ improvement of ICT competencies. In order to investigate the external and internal factors on the participants' ICT professional development experiences, a sequential explanatory design with mixed methods approach was used in the study. In the first phase, a questionnaire was used as the instrument to categorize participants into satisfactory ICT proficiency and less satisfactory ICT proficiency. The second phase was one-on-one interviews to find further information on the participants’ experiences on ICT professional development. The questionnaire was analyzed using SPSS, while interviews were analyzed using deductive content analysis which employs four stages in its process. Results show that all teachers with proper ICT proficiency and those who are less proficient in ICT have positive perceptions of the use of technology in education. However, there are differences in how they solve internal and external problems, and how they perceive guidance from peers and also support from the school environment. This study recommends universities and the government to develop programs of ICT professional development suitable for experienced female teachers.

Challenges of Green Transition in Polymer Production: Applications in Zero Energy Innovations and Hydrogen Storage.

The green transition in the sustainable production and processing of polymers poses multifaceted challenges that demand integral comprehensive solutions. Specific problems of presences of toxic trace elements are often missed and this prevents shifting towards eco-friendly alternatives. Therefore, substantial research and the development of novel approaches is needed to discover and implement innovative, sustainable production materials and methods. This paper is focused on the most vital problems of the green transition from the aspect of establishing universally accepted criteria for the characterization and classification of eco-friendly polymers, which is essential to ensuring transparency and trust among consumers. Additionally, the recycling infrastructure needs substantial improvement to manage the end-of-life stage of polymer products effectively. Moreover, the lack of standardized regulations and certifications for sustainable polymers adds to the complexity of this problem. In this paper we propose solutions from the aspect of standardization protocols for the characterization of polymers foreseen as materials that should be used in Zero Energy Innovations in Hydrogen Storage. The role model standards originate from eco-labeling procedures for materials that come into direct or prolonged contact with human skin, and that are monitored by different methods and testing procedures. In conclusion, the challenges of transitioning to green practices in polymer production and processing demands a concerted effort from experts in the field which need to emphasize the problems of the analysis of toxic ultra trace and trace impurities in samples that will be used in hydrogen storage, as trace impurities may cause terrific obstacles due to their decreasing the safety of materials. Overcoming these obstacles requires the development and application of current state-of-the-art methodologies for monitoring the quality of polymers during their recycling, processing, and using, as well as the development of other technological innovations, financial initiatives, and a collective commitment to fostering a sustainable and environmentally responsible future for the polymer industry and innovations in the field of zero energy applications.

Blockchain-Based Lean Supply Chain: A Simulation Approach

This paper aims to propose a model based on blockchain and cloud computing technologies to support lean production techniques for industrial supply chain management, evaluating how the combination of these technologies provides improvement in the chain performance. The literature review contextualizes the state of the art in studies related to the application of blockchain technology to lean manufacturing processes, as well as identifies research gaps in this field. Besides, this study models and simulates an architecture based on both the Hyperledger Fabric network and a virtual machine in the cloud environment, assessing its applicability and performance in the industrial supply chain. The analysis addresses lean aspects identified as research gaps, including integration of stakeholders in the collaborative production of customized products, conditions of flexibility and adaptability to demand variations, coordinated relationship of networks involving small and medium-sized enterprises, and behavior of various players acting simultaneously and consensually. The proposed model reveals a decentralized and nonlinear information sharing concept that demonstrates a logic of simultaneous participation of all players involved in the supply chain. The low costs and processing times identified in the simulation indicate the robustness of the system even in transactions involving a large number of companies and a large amount of data. This architecture offers an integration solution between stakeholders to support operational processes, providing insights for researchers and specialists in the adoption of innovative, reliable and inclusive information technologies for companies of different sizes or levels of development, with a focus on lean manufacturing, reduction in resource consumption and cost reduction. The developed model, which combines blockchain and cloud computing technologies applied to stages of lean production systems, presents a differentiated solution on the planning of integrated production systems, indicating the differential in this work.

Securing File Storage by Hybrid Cryptography

The proliferation of digital data in modern times necessitates robust security measures to safeguard confidentiality and integrity. This paper introduces a "File Storage System using Hybrid Cryptography," a pivotal solution addressing the pressing need for secure file storage and retrieval. Hybrid cryptography merges symmetric and asymmetric encryption techniques, ensuring a resilient and reliable data protection mechanism. This system leverages the strengths of symmetric encryption's speed and efficiency while integrating the key management advantages of asymmetric encryption. Through an exploration of historical cryptographic foundations, the emergence of hybrid cryptography, and contemporary file storage challenges, this paper highlights the importance of such an approach. The proposed system's phases, from encryption to decryption, elucidate its implementation and efficacy. Future research directions are outlined, focusing on enhanced key management, performance optimization, multi-platform integration, and user-centric solutions. Challenges such as quantum computing threats, scalability, and integration with emerging technologies are discussed. The conclusion emphasizes the significance of hybrid cryptography in addressing data security concerns amidst escalating digital data volumes, offering an efficient and secure framework for data storage and sharing. The research gaps identified prompt further exploration into quantum-resistant systems, scalability optimization, user-friendly interfaces, cross-cultural legal considerations, ethical implications, sustainability, and integration with emerging technologies.

Differential equations with maximal monotone operators

The paper deals with multivalued differential equations in abstract spaces. Nonlocal conditions are assumed. The model includes an m-dissipative multioperator which generates an equicontinuous, not necessarily compact, semigroup. The regularity of the nonlinear term also depends on the Hausdorff measure of noncompactness. The existence of integral solutions is discussed, with a topological index argument. A transversality condition is required. The results are applied to a partial differential inclusion in a bounded domain in Rn with nonlocal integral conditions. The model also includes an m-dissipative but not necessarily compact semigroup generated by a suitable subdifferential operator.

Integration of product development data for further ontological utilization

AbstractThe amount of data within the product development process requires a structured approach to coordinate them. Knowledge management solutions, such as ontologies, are a suitable way of linking data and representing semantic relationships. However, making all relevant data usable to ensure their target-oriented application is still a challenge. Thus, this contribution presents an approach to identify and classify heterogeneous data in product development. Besides this single ontology approach, interface solutions for data integration into an ontology are proposed.

Comparability of selected assays on the new cobas pro integrated solutions cobas ISE neo and cobas C 703 analytical units under routine-like conditions

Comparability of selected assays on the new cobas pro integrated solutions cobas ISE neo and cobas C 703 analytical units under routine-like conditions

Integral solution method of the laminar conjugated natural convection heat transfer from a hollow cylinder

The laminar conjugated natural convection heat transfer from a hollow cylinder is a common problem in engineering. The accurate calculation of the hot-spot temperature helps to monitor and evaluate the operating status of the equipment. In this paper, first, a mathematical model of the conjugated natural convection from a hollow cylinder is established. The boundary layer integral equations under arbitrary heat flux distribution on the surface are derived, and the optimal velocity and temperature profiles corresponding to different Prandtl numbers are determined. By combining the integral equations and the thermal network model, the hot-spot temperature and the average surface temperature of a hollow cylinder are solved iteratively. Subsequently, a computational fluid dynamic (CFD) simulation based on finite volume method is carried out to verify the accuracy of the integral solution method. The maximum relative error of the computed results of the two methods is 1.35%. The integral solution method performs much better in computation speed, increasing by 90 times. It is also found that as the thermal conductivity of solid materials decreases, although the hot-spot temperature increases, the average surface temperature remains basically unchanged. Finally, based on the lumped thermal equivalent circuit, the correlation of the Nusselt number corresponding to the hot-spot temperature is predicted. The parameters in the correlation are estimated by regression orthogonal design. The results show that under a wide range of solid thermal conductivity and fluid Prandtl numbers, the maximum error of the correlation is 6.02%. Therefore, this novel method is feasible and significant for calculating hot-spot temperature.

Result precision on the new cobas pro integrated solutions cobas ISE neo and cobas c 703 analytical units under routine-like conditions

Result precision on the new cobas pro integrated solutions cobas ISE neo and cobas c 703 analytical units under routine-like conditions